Patent ID: 12195583

BEST MODE

The above objects, other objects, features and advantages of the present invention will be readily understood through the following preferred embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the spirit of the present invention to those skilled in the art.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples.

Production Example: Production of Polyfunctional Compound

After substituting a 1,000 ml round-bottom flask with nitrogen, 268.16 g of DL-malic acid, 148.96 g of ethylene glycol and 0.02 g of monobutyltin oxide as a catalyst were introduced into the reactor and then subjected to an esterification reaction at 120° C. for 2 hours. When the theoretical amount of water generated as a byproduct of the reaction reached 2 moles, the reaction was determined to be complete, and the reaction was terminated, thus producing a polyfunctional compound. The process for producing this polyfunctional compound is shown in the following Reaction Scheme 1:

wherein m is an integer ranging from 2 to 30.

Example 1: Production of Biodegradable Aliphatic Polyester Resin Composition (1)

A 100-L reactor was substituted with nitrogen, and 29.23 kg of adipic acid, 22.53 kg of 1,4-butanediol and 300 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium isopropoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 210 minutes to obtain an aliphatic polyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 160° C. Thereafter, the reaction product obtained through the chain extension reaction introduced a was into solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 55° C. for 8 hours to obtain a final biodegradable resin composition.

Example 2: Production of Biodegradable Aliphatic Polyester Resin Composition (2)

A 100-L reactor was substituted with nitrogen, and 23.62 kg of succinic acid, 22.53 kg of 1,4-butanediol and 300 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 4 g of tetrabutyl titanate, 8 g of dibutyltin oxide and 8 g of titanium isopropoxide were added as a catalyst, and 15 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 181 minutes to obtain an aliphatic polyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 12 hours to obtain a final biodegradable resin composition.

Example 3: Production of Biodegradable Aliphatic Polyester Resin Composition (3)

A 100-L reactor was substituted with nitrogen, and 20.07 kg of succinic acid, 4.38 kg of adipic acid, 22.53 kg of 1,4-butanediol and 300 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased and finally set to 195° C., and then a theoretical amount of water was discharged. At this time, 6 g of tetrabutyl titanate, 7 g of dibutyltin oxide and 7 g of titanium isopropoxide were added as a catalyst, and 14 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 240° C. under a reduced pressure of 1.5 Torr for 192 minutes to obtain an aliphatic polyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 170° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a dehumidifier and subjected to a solid-state polymerization reaction at 80° C. for 12 hours to obtain a final biodegradable resin composition.

Example 4: Production of Biodegradable Aliphatic Polyester Resin Composition (4)

A 100-L reactor was substituted with nitrogen, and 22.91 kg of succinic acid, 0.88 kg of adipic acid, 22.08 kg of 1,4-butanediol, 0.3 kg of ethylene glycol and 350 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 189 minutes to obtain an aliphatic polyester resin composition. At this time, 20 g of tetrabutyl titanate were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 160° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a dehumidifier and subjected to a solid-state polymerization reaction at 85° C. for 10 hours to obtain a final biodegradable resin composition.

Example 5: Production of Biodegradable Aliphatic Polyester Resin Composition (5)

A 100-L reactor was substituted with nitrogen, and 23.62 kg of succinic acid, 21.4 kg of 1,4-butanediol, 0.75 kg of ethylene glycol and 350 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 194 minutes to obtain an aliphatic polyester resin composition. At this time, 20 g of tetrabutyl titanate were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 130° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 10 hours to obtain a final biodegradable resin composition.

Comparative Example 1

A 100-L reactor was substituted with nitrogen, and 29.23 kg of adipic acid and 23.53 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium isopropoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 320 minutes to obtain an aliphatic polyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 55° C. for 8 hours to obtain a final biodegradable resin composition.

Comparative Example 2

A 100-L reactor was substituted with nitrogen, and 23.62 kg of succinic acid and 22.53 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased and finally set to 203° C., and then a theoretical amount of water was discharged. At this time, 4 g of tetrabutyl titanate, 8 g of dibutyltin oxide and 8 g of titanium isopropoxide were added as a catalyst, and 15 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 286 minutes to obtain an aliphatic polyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 12 hours to obtain a final biodegradable resin composition.

Comparative Example 3

A 100-L reactor was substituted with nitrogen, and 20.07 kg of succinic acid, 4.38 kg of adipic acid and 22.53 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 6 g of tetrabutyl titanate, 7 g of dibutyltin oxide and 7 g of titanium isopropoxide were added as a catalyst, and 14 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 240° C. under a reduced pressure of 1.5 Torr for 348 minutes to obtain an aliphatic polyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 13 hours to obtain a final biodegradable resin composition.

Comparative Example 4

A 100-L reactor was substituted with nitrogen, and 22.91 kg of succinic acid, 0.88 kg of adipic acid, 22.08 kg of 1,4-butanediol and 0.3 kg of ethylene glycol were introduced into the reactor. The reaction temperature was increased and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 287 minutes to obtain an aliphatic polyester resin composition. At this time, 10 g of tetrabutyl titanate was added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 14 hours to obtain a final biodegradable resin composition.

Comparative Example 5

A 100-L reactor was substituted with nitrogen, and 23.62 kg of succinic acid, 21.4 kg of 1,4-butanediol and 0.75 kg of ethylene glycol were introduced into the reactor. The reaction temperature was increased and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 324 minutes to obtain an aliphatic polyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 11 hours to obtain a final biodegradable resin composition.

Experimental Example 1: Measurement of Molecular Weight, Melting Point and Melt Flow Index

The number-average molecular weight, weight-average molecular weight, melting point and melt flow index of each of the resin compositions produced by the methods of Examples 1 to 5 and Comparative Examples 1 to 5, were evaluated by the methods described below. The results of the evaluation are shown in Table 1 below.

[Evaluation Methods]

(1) Number-Average Molecular Weight and Weight-Average Molecular Weight

The number-average molecular weight and weight-average molecular weight distributions were measured by column chromatography using a system equipped with polystyrene at a temperature of 35° C. At this time, the developing solvent used was chloroform, the concentration of the sample used was 5 mg/mL, and the flow rate of the solvent was 1.0 mL/min.

(2) Melting Point

The melting point was measured using a differential scanning calorimeter at a temperature ranging from 20° C. to 200° C. at a temperature increase rate of 10° C. per minute under a nitrogen atmosphere.

(3) Melt Flow Index

The melt flow index was measured according to the ASTM D1238 standard under the conditions of 190° C. and 2, 160 g.

TABLE 1Number-weight-Polycon-averageaverageMelt flowdensationmolecularmolecularMeltingindexreactionweightweightpoint (° C.)(g/10 min)time (min)Example 151,250143,50065.45.2210Example 263,700183,450118.12.4181Example 366,280206,79097.12.6192Example 462,840209,250110.52.9189Example 563,700209,573111.03.2194Comparative22,30055,75064.862320Example 1Comparative26,30080,430117.836286Example 2Comparative24,25078,66095.241348Example 3Comparative27,50081,210110.039287Example 4Comparative23,20066,32010.9.642324Example 5

From the results in Table 1 above, it could be seen that Examples 1 to 5 had a higher number-average molecular weight and weigt-average molecular weight even for a short reaction time than Comparative Examples 1 to 5. In addition, it was found that Examples 1 to 5 had a lower melt flow index than Comparative Examples 1 to 5 and were advantageous in extrusion moldability and mechanical properties.

On the contrary, in the case of Comparative Examples 1 to 5, which do not contain the polyfunctional compound, the polycondensation reaction took a long time, the number-average molecular weight and the weight-average molecular weight were significantly lower than those of Examples 1 to 5 as a whole, and the melt flow index was very high, suggesting that the resin compositions of Comparative Examples 1 to 5 had poor extrusion formability, mechanical properties and durability.

Experimental Example 2: Evaluation of Mechanical Properties

The mechanical properties of the biodegradable resin composition produced in Examples 1 to 5 and Comparative Examples 1 to 5 were evaluated by the methods described below. The results of the evaluation are shown in Table 2 below.

[Evaluation Method]

The evaluation of mechanical properties was carried out by manufacturing a film having a thickness of 25 μm with an expansion ratio of 2.0 to 1 using a blown film machine having a screw diameter of 50 mm, a die gap of 2.2 mm, and a die diameter of 100 mm.

(1) Tensile Strength and Elongation

Tensile strength and elongation were measured using a universal test machine by preparing a specimen conforming to the ASTM D638 standard.

(2) Decomposition Evaluation

The sample prepared by the above method was recovered 12 months after burying at a depth of 30 cm from the soil surface and measured using the weight reduction method.

(3) Processability

Processability was visually observed for bubble stability and wrinkling during film production. At this time, as the Processability evaluation criteria, if the state of the film was good, it was indicated by ∘, if it was normal, it was indicated by Δ, and if it was bad, it was indicated by X.

TABLE 2TensilestrengthElongationBiodegrad-Process-(kgf/cm2)(%)ability (%)abilityExample 128520088.1ΔExample 238015081.2◯Example 335030083.5◯Example 435030085.6◯Example 537527580.6◯Comparative10515089.0XExample 1Comparative12510079.8XExample 2Comparative13512584..2ΔExample 3Comparative11015085.1ΔExample 4Comparative12510081.3XExample 5* Processability evaluation criteria.: ◯ Good, Δ Normal, X Bad

From the results in Table 2 above, it was confirmed that Example 1 to 5 had significantly increased mechanical properties of tensile strength, elongation, and processability compared to Comparative Examples 1 to 5. In addition, Examples 1 to 5 showed excellent biodegradability even in the result of biodegradability experiment.

On the other hand, Comparative Examples 1 to 5 showed excellent biodegradability of 79.88 or more, but this was only due to the low molecular weight, and on the contrary, as predicted from the melt flow index and molecular weight analysis results, tensile strength and elongation rate was significantly reduced, and processability was not good at an average or bad level.

Experimental Example 3: Evaluation of Weatherproof

After leaving the resin compositions prepared in Examples 1 to 5 and Comparative Examples 1 to 5 at a temperature of 25° C. and a relative humidity of 75%, samples were taken every 6 months to the change in number average molecular weight. The change in molecular weight was compared with the initial value. In addition, after leaving the film produced by the method of Experimental Example 2 at a temperature of 25° C. and a relative humidity of 75%, samples were collected every 6 months, tensile strength and elongation were measured, and the change over time was confirmed by comparing with the initial values.

TABLE 3Tensile strengthNumber-average(kgf/cm2)Elongation (%)molecular weightAfter 6After 12After 6After 12After 6After 12InitialmonthsmonthsInitialmonthsmonthsInitialmonthsmonthsExample 128526223720018416651,25049,71343,563Example 238035333415014013263,70062,42659,878Example 335031928730027324666,28064,95460,315Example 435032229430027625262,84059,69858,441Example 537536432327526723763,70063,63658,604Comparative10585531501227522,30018,50913,826Example 1Comparative12510066100805326,30021,30317,884Example 2Comparative13510570125986524,25019,64315,278Example 3Comparative11085531501167227,50022,82516,775Example 4Comparative1259960100794823,20018,83813,456Example 5

From the results in Table 3 above, in the case of Examples 1 to 5, compared to Comparative Examples 1 to 5, the width of the change over time of the physical properties and the decrease in the number average molecular weight were significantly smaller, and it was confirmed that the biodegradable resin composition according to the present invention had excellent weatherproof.

Example 6: Production of Biodegradable Aliphatic/Aromatic Copolyester Resin Composition (1)

A 100-L reactor was substituted with nitrogen, and 18.64 kg of dimethyl terephthalate, 10.81 kg of 1,4-butanediol, 300 g of the polyfunctional compound obtained in the Production Example, and 9.6 kg of tetrabutyl titanate as a catalyst were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 195° C., and then methanol was discharged. Then, 15.2 kg of adipic acid and 11.72 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium isopropoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 180 minutes to obtain an aliphatic/aromatic copolyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 160° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Example 7: Production of Biodegradable Aliphatic/Aromatic Copolyester Resin Composition (2)

A 100-L reactor was substituted with nitrogen, and 21.36 kg of dimethyl terephthalate, 22.53 kg of 1,4-butanediol, 310 g of the polyfunctional compound obtained in the Production Example, and 10.4 kg of tetrabutyl titanate as a catalyst were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 200° C., and then methanol was discharged. Then, 13.15 kg of adipic acid was introduced into the reactor. The reaction temperature was increased and finally set to 203° C., and then a theoretical amount of water was discharged. At this time, 8 g of dibutyltin oxide and 8 g of titanium isopropoxide were added as a catalyst, and 15 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 188 minutes to obtain an aliphatic/aromatic copolyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 12 hours to obtain a final biodegradable resin composition.

Example 8: Production of Biodegradable Aliphatic/Aromatic Copolyester Resin Composition (3)

A 100-L reactor was substituted with nitrogen, and 17.48 kg of dimethyl terephthalate, 22.53 kg of 1,4-butanediol, 300 g of the polyfunctional compound obtained in the Production Example, and 10.4 kg of tetrabutyl titanate as a catalyst were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 195° C., methanol was discharged. Then, 16.08 kg of succinic acid was added to the reactor, the reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 7 g of dibutyltin oxide and 7 g of titanium isopropoxide were added as a catalyst, and 14 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 240° C. under a reduced pressure of 1.5 Torr for 164 minutes to obtain an aliphatic/aromatic copolyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 170° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 12 hours to obtain a final biodegradable resin composition.

Example 9: Production of Biodegradable Aliphatic/Aromatic Copolyester Resin Composition (4)

A 100-L reactor was substituted with nitrogen, and 14.95 kg of isophthalic acid, 13.0 kg of succinic acid, 23.43 kg of 1,4-butanediol, and 350 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 162) obtain an aliphatic/aromatic copolyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 160° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a dehumidifier and subjected to a solid-state polymerization reaction at 80° C. for 10 hours to obtain a final biodegradable resin composition.

Example 10: Production of Biodegradable Aliphatic/Aromatic Copolyester Resin Composition (5)

A 100-L reactor was substituted with nitrogen, and 15.95 kg of isophthalic acid, 12.28 kg of succinic acid, 23.43 kg of 1,4-butanediol, and 350 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of to obtain an aliphatic/aromatic 1.5 Torr for 192 minutes copolyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 130° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 10 hours to obtain a final biodegradable resin composition.

Example 11: Production of Biodegradable Aliphatic/Aromatic Copolyester Resin Composition (6)

A 100-L reactor was substituted with nitrogen, and 15.95 kg of phthalic acid, 15.2 kg of adipic acid, 23.43 kg of 1,4-butanediol, and 400 g of the polyfunctional compound obtained in the Production Example were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 238° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of tetrabutyl titanate were added as a catalyst, and 15 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 162 minutes to obtain an aliphatic/aromatic copolyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 130° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 85° C. for 10 hours to obtain a final biodegradable resin composition.

Comparative Example 6

A 100-L reactor was substituted with nitrogen, and 18.64 kg of dimethyl terephthalate, 10.81 kg of 1,4-butanediol and 9.6 kg of tetrabutyl titanate as a catalyst were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 195° C., and then methanol was discharged. Then, 15.2 kg of adipic acid and 11.72 kg of 1,4-butanediol were introduced into the reactor, the reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium isopropoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of for 1.5 Torr 252 minutes to obtain an aliphatic/aromatic copolyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Comparative Example 7

A 100-L reactor was substituted with nitrogen, and 21.36 kg of dimethyl terephthalate, 22.53 kg of 1,4-butanediol and 10.4 kg of tetrabutyl titanate as a catalyst were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 200° C., and then methanol was discharged. Then, 13.15 kg of adipic acid was introduced into the reactor, the reaction temperature was increased and finally set to 203° C., and then a theoretical amount of water was discharged. At this time, 8 g of dibutyltin oxide and 8 g of titanium isopropoxide were added as a catalyst, and 15 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 245° C. under a reduced pressure of 1.5 Torr for 268 minutes to obtain an aliphatic/aromatic copolyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Comparative Example 8

A 100-L reactor was substituted with nitrogen, and 17.48 kg of dimethyl terephthalate, 22.53 kg of 1,4-butanediol and 10.4 kg of tetrabutyl titanate as a catalyst were introduced into the reactor. The reaction temperature was increased and finally set to 195° C., and then methanol was discharged. Then, 16.08 kg of succinic acid was introduced into the reactor, the reaction temperature was increased and finally set to 205° C., and then a theoretical amount of water was discharged. At this time, 7 g of dibutyltin oxide and 7 g of titanium isopropoxide were added as a catalyst, and 14 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 240° C. under a reduced pressure of 1.5 Torr for 366 minutes to obtain an aliphatic/aromatic copolyester resin composition. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Comparative Example 9

A 100-L reactor was substituted with nitrogen, and 14.95 kg of phthalic acid, 13.0 kg of succinic acid, 23.43 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 292 minutes to obtain an aliphatic/aromatic copolyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Comparative Example 10

A 100-L reactor was substituted with nitrogen, and 15.95 kg of phthalic acid, 12.28 kg of succinic acid, 23.43 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 235° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of titanium propoxide were added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 325 minutes to obtain an aliphatic/aromatic copolyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Comparative Example 11

A 100-L reactor was substituted with nitrogen, and 15.95 kg of phthalic acid, 15.2 kg of adipic acid, 23.43 kg of 1,4-butanediol were introduced into the reactor. The reaction temperature was increased while stirring and finally set to 238° C., and then a theoretical amount of water was discharged. At this time, 10 g of dibutyltin oxide and 10 g of tetrabutyl titanate were added as a catalyst, and 15 g of trimethyl phosphate was added as a stabilizer. Thereafter, the temperature of the reactor was increased, and a polycondensation reaction was performed at a temperature of 250° C. under a reduced pressure of 1.5 Torr for 328 minutes to obtain an aliphatic/aromatic copolyester resin composition. At this time, 20 g of tetrabutyl titanate was added as a catalyst, and 20 g of trimethyl phosphate was added as a stabilizer. Then, 100 kg of the resin composition obtained through the polycondensation reaction and 500 g of 1,6-hexamethylene diisocyanate were mixed together using a supermixer, and then subjected to a chain extension reaction using a twin screw extruder having a diameter of 58 mm at 125° C. Thereafter, the reaction product obtained through the chain extension reaction was introduced into a solid-state polymerization apparatus equipped with a vacuum pump and subjected to a solid-state polymerization reaction at 80° C. for 8 hours to obtain a final biodegradable resin composition.

Experimental Example 4: Measurement of Molecular Weight, Melting Point and Melt Flow Index

The number-average molecular weight, weight-average molecular weight, melting point and melt flow index of each of the resin compositions produced by the methods of Examples 6 to 11 and Comparative Examples 6 to 11, were evaluated in the same manner as in Experimental Example 1 above. The results of the evaluation are shown in Table 4 below.

TABLE 4Number-weight-averageaverageMeltingMelt flowPolycondensationmolecularmolecularpointindexreactionAcid valueweightweight(° C.)(g/10 min)time (min)(mgKOH/g)Example 653,020158,000125.43.31800.97Example 759,000184,080148.02.81881.25Example 854,300165,500121.33.11640.85Example 948,280159,800120.44.11620.80Example 1062,500180,625125.12.11922.0Example 1155,700169,885124.83.11821.38Comparative18,34549,531125.052.13823.7Example 6Comparative16,10050,692148.263.12983.5Example 7Comparative20,20048,320120.248.43663.8Example 8Comparative17,25049,680120.950.64395.2Example 9Comparative16,88050,320124.349.24254.8Example 10Comparative17,03038,220123.447.74084.3Example 11

From the results in Table 4 above, it could be seen that Examples 6 to 11 had a higher number-average molecular weight and weight-average molecular weight even for a short reaction time than Comparative Examples 6 to 11. In addition, it was found that Examples 6 to 11 had a lower melt flow index and acid value than Comparative Examples 6 to 11 and were advantageous in extrusion moldability and mechanical properties.

On the contrary, in the case of Comparative Examples 6 to 11, which do not contain the polyfunctional compound, the polycondensation reaction took a long time, the acid value was high due to increased reverse reaction by long reaction time, the number-average molecular weight and the weight-average molecular weight were significantly lower than those of Examples 6 to 11 as a whole, and the melt flow index was very high, suggesting that the resin compositions of Comparative Examples 6 to 11 had poor extrusion formability, mechanical properties and durability.

Experimental Example 5: Evaluation of Mechanical Properties

The mechanical properties of the biodegradable resin composition produced in Examples 6 to 11 and Comparative Examples 6 to 11 were evaluated in the same manner as in Experimental Example 2 above. The results of the evaluation are shown in Table 5 below.

TABLE 5TensilestrengthElongationBiodegrad-Process-(kgf/cm2)(%)ability (%)abilityExample 632548078.3◯Example 735240074.2◯Example 831250078.5◯Example 930857581.8◯Example 1031854580.6◯Example 1131653880.9ΔComparative12525080.0XExample 6Comparative13220077.8ΔExample 7Comparative12822579.2XExample 8Comparative11017580.1XExample 9Comparative11712582.3XExample 10Comparative9811583.1XExample 11* Processability evaluation criteria.: ◯ Good, Δ Normal, X Bad

From the results in Table 5 above, it was confirmed that Example 6 to 11 had significantly increased mechanical properties of tensile strength, elongation, and processability compared to Comparative Examples 6 to 11. In addition, Examples 6 to 11 showed excellent biodegradability even in the result of biodegradability experiment.

On the other hand, Comparative Examples 6 to 11 showed excellent biodegradability of 77% or more, but this was only due to the low molecular weight, and on the contrary, as predicted from the melt flow index and molecular weight analysis results, tensile strength and elongation rate was significantly reduced, and processability was not good at an average or bad level.

Experimental Example 6: Evaluation of Weatherproof

After leaving the resin compositions prepared in Examples 6 to 11 and Comparative Examples 6 to 11 at a temperature of 25° C. and a relative humidity of 75%, samples were taken every 6 months to the change in number average molecular weight. The change in molecular weight was compared with the initial value. In addition, after leaving the film produced by the method of Experimental Example 5 at a temperature of 25° C. and a relative humidity of 75%, samples were collected every 6 months, tensile strength and elongation were measured, and the change over time was confirmed by comparing with the initial values.

TABLE 6Tensile strengthNumber-average(kgf/cm2)Elongation (%)molecular weightAfter 6After 12After 6After 12After 6After 12InitialmonthsmonthsInitialmonthsmonthsInitialmonthsmonthsExample 632531931748047346553,02052,22551,320Example 735234334240039737559,00058,52056,995Example 831231030150049348054,30053,45052,620Example 930830429557556455048,28047,30046,690Example 1031831130654553452562,50061,10059,000Example 1131631430553852351555,70054,15053,110Comparative12510777.625021015018,30015,65011,390Example 6Comparative13211077.520016511016,10013,3959,451Example 7Comparative12810980.822519014020,20017,21012,846Example 8Comparative1109572.817515012017,25014,87011,420Example 9Comparative11710178.51251058516,80014,63511,500Example 10Comparative988058.2115957517,10013,82810,100Example 11

From the results in Table 3 above, in the case of Examples 6 to 11, compared to Comparative Examples 6 to 11, the width of the change over time of the physical properties and the decrease in the number average molecular weight were significantly smaller, and it was confirmed that the biodegradable resin composition according to the present invention had excellent weatherproof.