Patent ID: 11932725
Assignee: ECOVANCE CO. LTD.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  Y | IPC C

Claim 7:
8. A process for preparing a biodegradable polyester resin, which comprises:
a first step of mixing a diol component and an aromatic dicarboxylic acid and pretreating it to obtain a slurry;
a second step of subjecting a mixture comprising the slurry and an aliphatic dicarboxylic acid; or a mixture of a reaction product obtained by esterification of the slurry and an aliphatic dicarboxylic acid to an esterification reaction at least once to obtain a prepolymer; and
a third step of subjecting the prepolymer to a polycondensation reaction,
wherein the biodegradable polyester resin comprises a polymer having a first repeat unit and a second repeat unit,
wherein the first repeat unit comprises a first diol residue and an aromatic dicarboxylic acid residue, and the second repeat unit comprises a second diol residue and an aliphatic dicarboxylic acid residue, the first and second diol residues each comprise a residue of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof, the aromatic dicarboxylic acid residue comprises a residue of terephthalic acid, dimethyl terephthalate, or a derivative thereof, the aliphatic dicarboxylic acid residue comprises a residue of adipic acid, succinic acid, sebacic acid, or a derivative thereof,
the number of the first repeat unit is 100 to 900,
the number of the second repeat unit is 100 to 1,100, and
a loss tangent (tan δ) represented by the following Equation 3 is greater than 1:

Loss tangent (tan δ)=G″/G′  [Equation 3]

in Equation 3, G′ is the storage modulus of a biodegradable polyester sheet prepared from the biodegradable polyester resin at 240° C. and a frequency of 5 rad/s in dynamic viscoelasticity measurement, and
G″ is the loss modulus of the biodegradable polyester sheet prepared from the biodegradable polyester resin at 240° C. and a frequency of 5 rad/s in dynamic viscoelasticity measurement,
wherein the loss modulus (G″) of the biodegradable polyester resin is 220,000 dyne/cm2 to 400,000 dyne/cm2.