Polyester resin as well as preparation method and application thereof

The invention relates to the technical field of coating resin, in particular to polyester resin as well as a preparation method and application thereof. The polyester resin is at least obtained by reacting a linear polyamide oligomer, polyol, polyacid and an acidolysis agent, and the acid value of the polyester resin is 15-70 mg KOH/g. The polyester resin provided by the invention has proper acid value, melt viscosity and other indexes; the powder coating prepared from the polyester resin can be applied to the transfer printing aspect of coiled materials, is completely cured at 250 DEG C for 60 seconds, does not adhere to paper in the coating transfer printing process, is clear in transfer printing pattern, is subjected to a T-bend test of 0T after being placed for one year after transfer printing, and does not generate a powder caking phenomenon after being stored for 24 hours at 40 DEG C; compared with the existing coiled material powder coating, the coiled material powder coating has better heat transfer p