Method for producing polybutylene terephthalate

1. A method for producing polybutylene terephthalate, the method comprising:

(a) subjecting a diol component comprising a biomass-derived raw material 1,4-butanediol having a nitrogen content of from 0.01 to 20 ppm by mass and a dicarboxylic acid component comprising terephthalic acid or an alkyl terephthalate to an esterification reaction or ester-exchange reaction,

(b) subjecting the reactant obtained in (a) to a polycondensation reaction, thereby obtaining polybutylene terephthalate, and

further comprising directly producing the biomass-derived raw material 1,4-butanediol or a biomass-derived crude 1,4-butanediol from at least one carbon source selected from the group consisting of glucose, fructose, xylose, and saccharose by a fermentation method, and

obtaining the biomass-derived raw material 1,4-butanediol by purifying the biomass-derived crude 1,4-butanediol before the subjecting (a),

wherein a content of gamma butyrolactone in the biomass-derived raw material 1,4-butanediol is from 1 to 100 ppm by mass.

2. The method according to claim 1 , wherein the content of gamma butyrolactone in the crude 1,4-butanediol is from 101 ppm by mass to 2% by mass.

3. The method according to claim 1 , wherein a content of 1-acetoxy-4-hydroxybutane in the raw material 1,4-butanediol is from 1 to 99 ppm by mass.

4. The method according to claim 1 , further comprising producing the biomass-derived raw material 1,4-butanediol or the biomass-derived crude 1,4-butanediol from a biomass material using a non-natural microorganism biocatalyst, wherein the non-natural microorganism biocatalyst comprises a microorganism containing at least one exogenous nucleic acid fragment coding 4-hydroxybutanoic acid dehydrogenase, succinyl-CoA synthetase, CoA-dependent succinate-semialdehyde dehydrogenase or α-ketoglutarate decarboxylase and having a 4-hydroxybutanoic acid biosynthesis pathway and in which the microorganism comprises the exogenous nucleic acid fragment in an amount sufficient to secrete a monomer of 4-hydroxybutanoic acid.

5. The method according to claim 1 , wherein a content of the terephthalic acid or alkyl terephthalate based on the total of the dicarboxylic acid component is 80 mol % or more.

6. The method according to claim 1 , wherein a content of the biomass-derived raw material 1,4-butanediol is 80 mol % or more based on the total of the diol component.

7. The method according to claim 1 , wherein the dicarboxylic acid component further comprises at least one other dicarboxylic acid.

8. The method according to claim 1 , wherein the diol component further comprises at least one other diol.

9. The method according to claim 4 , wherein the microorganism is selected from the group consisting of Escherichia coli, Anaerobiospirillum, Actinobacillus, filamentous fungi and yeast.

10. The method according to claim 1 , wherein the content of nitrogen in the biomass-derived raw material 1,4-butanediol is from 0.1 to 5 ppm by mass.

11. The method according to claim 1 , wherein the content of the gamma butyrolactone in the biomass-derived raw material 1,4-butanediol is from 1 to 50 ppm by mass.

12. The method according to claim 1 , wherein the content of the gamma butyrolactone in the biomass-derived raw material 1,4-butanediol is from 5 to 20 ppm by mass.

13. The method according to claim 1 , wherein the content of the gamma butyrolactone in the biomass-derived raw material 1,4-butanediol is from 150 ppm to 2% by mass.

14. The method according to claim 4 , wherein the content of 1-acetoxy-4-hydroxybutane in the raw material 1,4-butanediol is from 5 to 80ppm by mass.

15. The method according to claim 1 , wherein the polycondensation reaction is conducted at a temperature from 180° C. to 260° C. and a pressure from 10 kPa to 133 kPa for 0.5 hours to 5 hours in the presence of an esterification catalyst in a single step or multiple steps.