Abstract: An object is to provide a crosslinked polyester resin that does not lose bond exchange activity even when immersed in water, an organic solvent, or the like and in which bond exchange is fast. Another object is to provide a polyester resin in which bond exchange is fast. A crosslinked polyester resin in which a polyester resin having a plurality of side chains each having a carboxy group and a plurality of side chains each having a tertiary amino group is crosslinked by an epoxy-based crosslinking agent having a plurality of epoxy groups.

Abstract: An object of the present invention is to provide a polyester resin that has a high degree of freedom in design and that can have excellent biodegradability even with an increased molecular weight. A polyester of the present invention contains a hydroxy group-containing dicarboxylic acid component and a diol component (excluding a hydroxy group-containing dicarboxylic acid component) as copolymerization components, wherein more than 50 mol % of an aliphatic diol component is contained in 100 mol % of the diol component, the polyester has a number average molecular weight of 3000 or higher, and the polyester has a total hydroxyl value of 1000 eq/ton or higher.

Abstract: An object is to provide a crosslinked polyester resin that has high strength at room temperature but is capable of reprocessing, adhesion between films, and self-repair at a softening temperature thereof or higher, due to dynamic covalent crosslinks allowing bond exchange at high temperatures, that exhibits softening behavior due to bond exchange by a transesterification reaction even without containing any transesterification catalyst, and that exhibits self-adhesiveness, remoldability, and scratch repair properties. A crosslinked polyester resin in which a polyester resin having a carboxy group on a side chain is crosslinked by an epoxy-based crosslinking agent having a plurality of epoxy groups, wherein the epoxy-based crosslinking agent includes an epoxy amine compound having two or more tertiary amino groups and two or more epoxy groups in a molecule, and an amount of the epoxy amine compound is 3 to 30 parts by mole per 100 parts by mole of the carboxy group of the polyester resin.

Abstract: An object is to provide a crosslinked aromatic polyester resin composition that has high strength at room temperature and is capable of reprocessing, adhering films to each other, and self-repairing at a bond exchange activation temperature thereof or higher, due to “dynamic” covalent crosslinks allowing bond exchange at high temperatures.

Abstract: The present invention provides an aromatic polyester having several operative functional groups and a method for producing same. An aromatic polyester comprising a polycarboxylic acid component and a polyhydric alcohol component as a copolymerization component, wherein the aromatic polyester comprises a polycarboxylic acid component having an operative functional group by 50 mol % or more when a total amount of the polycarboxylic acid component is taken as 100 mol %, and the aromatic polyester comprises an aromatic polyhydric alcohol component by 50 mol % or more when a total amount of the polyhydric alcohol component is taken as 100 mol %.