Polyester resin, method for manufacturing polyester resin, and coating composition containing polyester resin
The present invention relates to a polyester resin with excellent solubility in generic solvents, especially with excellent solubility at a temperature of 0° C. or lower. According to the present invention, by using the polyester resin with excellent solubility in generic solvents, solubility at a lower temperature, especially the solubility at a temperature of 0° C. or lower, is enhanced, making it easier to prepare paints, coatings and the like. The polyester resin related to the present invention contains 0.05 to 0.5 mol of an isosorbide-derived structural unit and 0.015 to 0.4 mol of a trihydric or higher alcohol-derived structural unit relative to 1 mol of a polycarboxylic acid-derived structural unit.
1. A polyester resin, comprising:
a polycarboxylic acid-derived structural unit;
a trihydric or higher alcohol-derived structural unit;
an isosorbide-derived structural unit; and
a structural unit derived from a dihydric alcohol that is other than isosorbide and having an alicyclic skeleton,
wherein 0.05 to 0.5 mol of the isosorbide-derived structural unit and 0.015 to 0.4 mol of the trihydric or higher alcohol-derived structural unit are present relative to 1 mol of the polycarboxylic acid-derived structural unit, and
where the structural unit derived from the dihydric alcohol having an alicyclic skeleton is present at 0.001 to 0.15 mol relative to 1 mol of the polycarboxylic acid-derived structural unit.
2. The polyester resin according to claim 1 , wherein the trihydric or higher alcohol-derived structural unit is present at 0.015 to 0.2 mol relative to 1 mol of the polycarboxylic acid-derived structural unit.
3. The polyester resin according to claim 1 , wherein the isosorbide-derived structural unit is present at 0.05 to 0.4 mol relative to 1 mol of the polycarboxylic acid-derived structural unit.
4. The polyester resin according to claim 1 , wherein the dihydric alcohol having an alicyclic skeleton is 1,4-cyclohexanedimethanol.
5. The polyester resin according to claim 1 , wherein the glass transition temperature is 50 to 90° C.
6. A method for manufacturing the polyester resin according to claim 1 , comprising:
polycondensing a polycarboxylic acid component and a polyhydric alcohol component,
wherein the polyhydric alcohol component comprises 0.05 to 0.5 mol of isosorbide, 0.015 to 0.4 mol of a trihydric or higher alcohol and 0.001 to 0.15 mol of an alicyclic dihydric alcohol relative to 1 mol of the polycarboxylic acid component.
7. A polyester resin solution, comprising the polyester resin according to claim 1 and a solvent.
8. The polyester resin solution according to claim 7 , wherein the solvent is an organic solvent.
9. A coating composition, comprising the polyester resin solution according to claim 7 .
10. The coating composition according to claim 9 , wherein the polyester resin according to claim 1 is present at 5 to 60 mass % of the total mass of the polyester resin solution.