Biodegradable molded article and biodegradable polyester resin composition

1. A biodegradable molded article, comprising: a polyester resin comprising a diol, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid,

wherein a biodegradability per hydrolysis degree of the biodegradable molded article is 1.4 or more,

wherein the biodegradability per hydrolysis degree is obtained by dividing a biodegradability after nine weeks by a hydrolysis degree after one week,

wherein the diol includes 1,4-butandiol in a content of about 98 mol % or more based on the total diol,

wherein the aromatic dicarboxylic acid includes terephthalic acid or dimethyl terephthalate in a content of about 43 mol % to about 53 mol % based on the total dicarboxylic acid,

wherein the aliphatic dicarboxylic acid includes adipic acid, in a content of about 47 mol % to about 57 mol % based on the total dicarboxylic acid,

wherein the biodegradability after nine weeks and the hydrolysis degree after one week are measured by the measurement method below:

in the measurement method, the biodegradability after nine weeks is a molecular weight reduction rate, compared to an initial molecular weight of the biodegradable molded article, of the biodegradable molded article processed into flakes having a thickness of 300 μm and a size of 30 mm=30 mm and placed at 60° C. and a relative humidity of 90% for 63 days under composting conditions, and

the hydrolysis degree after one week is a molecular weight reduction rate, compared to an initial molecular weight of the biodegradable molded article, of the flakes placed at 80° C. and a relative humidity of 100% for 7 days.

2. The biodegradable molded article according to claim 1 , comprising nanocellulose that has an average diameter ranging from 0.5 nm to 10 nm and an average length ranging from 20 nm to 300 nm, and the polyester resin comprises a metal.

3. The biodegradable molded article according to claim 2 , wherein the metal comprises a metal salt and a silicon element is included in the polyester resin,

wherein a mass ratio of a metal element contained in the metal salt to the silicon element ranges from 0.1 to 0.7.

4. A biodegradable polyester resin composition, comprising: a polyester resin comprising a diol, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid,

wherein a biodegradability per hydrolysis degree of the biodegradable polyester resin composition is 1.35 or more,

wherein the biodegradability per hydrolysis degree is obtained by dividing a biodegradability after nine weeks by a hydrolysis degree after one week,

wherein the diol includes 1,4-butandiol in a content of about 98 mol % or more based on the total diol,

wherein the aromatic dicarboxylic acid includes terephthalic acid or dimethyl terephthalate in a content of about 43 mol % to about 53 mol % based on the total dicarboxylic acid,

wherein the aliphatic dicarboxylic acid includes adipic acid, in a content of about 47 mol % to about 57 mol % based on the total dicarboxylic acid,

wherein the biodegradability after nine weeks and the hydrolysis degree after one week are measured by the measurement method below:

in the measurement method, the biodegradability after nine weeks is a molecular weight reduction rate, compared to an initial molecular weight of the biodegradable polyester resin composition, of the biodegradable polyester resin composition processed into flakes having a thickness of 300 μm and a size of 30 mm×30 mm and placed at 60° C. and a relative humidity of 90% for 63 days under composting conditions, and

the hydrolysis degree after one week is a molecular weight reduction rate, compared to an initial molecular weight of the biodegradable polyester resin composition, of the flakes placed at 80° C. and a relative humidity of 100% for 7 days.

5. The biodegradable polyester resin composition according to claim 4 , wherein the biodegradability after nine weeks is 75% or more, and the hydrolysis degree after one week is 60% or less.

6. The biodegradable polyester resin composition according to claim 4 , wherein a biodegradability after one week of the biodegradable polyester resin composition ranges from 45% to 75%,

wherein the biodegradability after one week is a molecular weight reduction rate, compared to an initial biodegradability of the flakes, of the flakes placed at 60° C. and a relative humidity of 90% for 7 days under composting conditions.

7. The biodegradable polyester resin composition according to claim 4 , wherein a hydrolysis degree after nine weeks of the biodegradable polyester resin composition is 80% or more,

wherein the hydrolysis degree after nine weeks is a molecular weight reduction rate, compared to an initial hydrolysis degree of the flakes, of the flakes placed at 80° C. and a relative humidity of 100% for 63 days.

8. The biodegradable polyester resin composition according to claim 4 , wherein an acid value of the biodegradable polyester resin composition is 2.0 mg KOH/g or less.

9. The biodegradable polyester resin composition according to claim 4 , wherein a biodegradability increase rate from one week to four weeks of the biodegradable polyester resin composition ranges from 3.5%/week to 8%/week.

10. The biodegradable polyester resin composition according to claim 9 , wherein a hydrolysis degree increase rate from one week to two weeks of the biodegradable polyester resin composition ranges from 29%/week to 50%/week, and

a hydrolysis degree increase rate from three weeks to six weeks of the biodegradable polyester resin composition ranges from 0.01%/week to 3%/week.

11. The biodegradable polyester resin composition according to claim 9 , wherein a hydrolysis degree increase rate from two weeks to three weeks of the biodegradable polyester resin composition ranges from 3%/week to 10%/week.

12. The biodegradable polyester resin composition according to claim 4 , comprising a metal salt and a silicon element,

wherein a mass ratio of a metal element contained in the metal salt to the silicon element ranges from 0.1 to 0.7.

13. A biodegradable polyester resin composition, comprising a polyester resin comprising a diol, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid,

wherein a biodegradability per aliphatic carboxylic acid of the biodegradable polyester resin composition is 1.7 or more,

wherein the biodegradability per aliphatic carboxylic acid is obtained by dividing a biodegradability after nine weeks by a ratio the aliphatic dicarboxylic acid to a total of dicarboxylic acids,

wherein the diol includes 1,4-butandiol in a content of about 98 mol % or more based on the total diol,

wherein the aromatic dicarboxylic acid includes terephthalic acid or dimethyl terephthalate in a content of about 43 mol % to about 53 mol % based on the total dicarboxylic acid,

wherein the aliphatic dicarboxylic acid includes adipic acid, in a content of about 47 mol % to about 57 mol % based on the total dicarboxylic acid,

wherein the biodegradability after nine weeks is 85% or more, and the biodegradability after nine weeks is measured by the measurement method below:

in the measurement method, the biodegradability after nine weeks is a molecular weight reduction rate, compared to a molecular weight of the biodegradable polyester resin composition, the biodegradable polyester resin composition placed at 60° C. and a relative humidity of 90% for 9 weeks under composting conditions.

14. The biodegradable polyester resin composition according to claim 13 , wherein the biodegradability after nine weeks is 88% or more.

15. The biodegradable polyester resin composition according to claim 13 , wherein a biodegradability after one week of the biodegradable polyester resin composition ranges from 45% to 65%,

wherein the biodegradability after one week is a molecular weight reduction rate, compared to an initial biodegradability of the biodegradable polyester resin composition, of the biodegradable polyester resin composition placed at 60° C. and a relative humidity of 90% for one week under composting conditions.

16. The biodegradable polyester resin composition according to claim 14 , wherein a biodegradability after two weeks of the biodegradable polyester resin composition ranges from 55% to 70%,

wherein the biodegradability after two weeks is a molecular weight reduction rate, compared to an initial biodegradability of the biodegradable polyester resin composition, of the biodegradable polyester resin composition placed at 60° C. and a relative humidity of 90% for two weeks under composting conditions.

17. The biodegradable polyester resin composition according to claim 16 , wherein a biodegradability increase rate from one week to two weeks of the biodegradable polyester resin composition ranges from about 4%/week to about 15%/week.

18. The biodegradable polyester resin composition according to claim 13 , wherein a biodegradability after four weeks of the biodegradable polyester resin composition ranges from 73% to 85%,

wherein the biodegradability after four weeks is a number average molecular weight reduction rate, compared to an initial number average molecular weight of the biodegradable polyester resin composition, of the biodegradable polyester resin composition placed for four weeks under high-temperature and high-humidity conditions of 80° C. and a relative humidity of 100%, and

a biodegradability increase rate from one week to four weeks of the biodegradable polyester resin ranges from 3.5%/week to 8%/week.

19. The biodegradable polyester resin composition according to claim 13 , wherein a hydrolysis degree after one week of the biodegradable polyester resin composition ranges from 35% to 60%,

wherein the hydrolysis degree after one week is a number average molecular weight reduction rate, compared to an initial hydrolysis degree of the biodegradable polyester resin composition, of the biodegradable polyester resin composition placed for one week under high-temperature and high-humidity conditions of 80° C. and a relative humidity of 100%.

20. The biodegradable polyester resin composition according to claim 13 , comprising a nitrogen element.