Method for producing biodegradable polyester and biodegradable polyester produced by the method

Abstract

To provide a method for manufacturing a biodegradable polyester with suppressed discoloration, which can be used for applications such as disposable film, tableware, and agricultural film and to provide a biodegradable polyester produced by the same method.SOLUTION: There is provided a process for preparing a biodegradable polyester, which comprises: (1) subjecting a reaction mixture comprising (a) a dicarboxylic acid component comprising an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid, (b) a diol component comprising an aliphatic diol having a short chain length of less than 4 carbon atoms, and (c) a discoloration inhibitor to an esterification reaction or a transesterification reaction in the presence of the entire amount of a catalyst, or a part thereof, to obtain a prepolymer; and (2) subjecting the prepolymer to a polycondensation reaction in the presence of a stabilizer and the remainder of the catalyst, or without the addition of the catalyst, to obtain a biodegradable polyester, wherein the discoloration inhibitor includes at least one selected from the group consisting of glycerol, trimethylolpropane, and pentaerythritol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing biodegradable polyester with suppressed discoloration, and a method for producing the same. Specifically, the present invention relates to a biodegradable polyester prepared from aliphatic dicarboxylic acids. Dicarboxylic acids, aromatic dicarboxylic acids, and short aliphatic diols with chain lengths of less than four carbon atoms and a method for producing biodegradable polyester with reduced discoloration using the same. This relates to biodegradable polyesters produced by [Background technology]

[0002] In recent years, the seriousness of environmental issues has been recognized worldwide, and environmental regulations have been strengthened accordingly. Research is being conducted into materials that can replace general-purpose plastics while reducing environmental pollution. Among these, biodegradable plastics that can be naturally decomposed under certain conditions are being actively developed. Black carbon has attracted considerable interest as an alternative material that can be used to manufacture a variety of disposable household products. In particular, 1,4-butanediol and adipic acid, terephthalic acid, or dimethyl Poly(butylene adipate-co-terephthalate) can be prepared by reacting Polybutadiene-Based Acetone (PBAT) is currently widely used as a biodegradable polyester.

[0003] The physical properties of poly(butylene adipate-co-terephthalate) vary depending on the manufacturer. However, the common target properties are high molecular weight and intrinsic viscosity, low acid value, and high These properties are basically due to the biodegradable polyester. The glass transition temperature, melting point, and other material-specific properties are related to the durability and processability of the steel. By adjusting the temperature, crystallinity, stiffness, ductility, biodegradation rate, etc., we are able to create biodegradable polymers suitable for new applications. To develop esters, the type of dicarboxylic acid and its content can be changed. The method should be applied.

[0004] For example, polybutylene succinate, polybutylene succinate adipate, polybutylene Polyisosorbide succinate, polybutylene succinate adipate terephthalate, etc. As shown in the previous report, the development of biodegradable polyesters based on 1,4-butanediol has been reported. (See Non-Patent Document 1, Non-Patent Document 2, Patent Document 1, etc.).

[0005] On the other hand, aliphatic diol compounds with a chain length of less than 4 carbon atoms, especially ethylene glycol Although it is more cost competitive than 1,4-butanediol, There have been few reports on the production methods of biodegradable polyesters. Recycle-based biodegradable polyester is a 1,4-butanediol-based polyester. It has different physical properties from conventional biodegradable resins, so it can be used to replace existing biodegradable resins or to be applied to other fields. There is a possibility that this could be done. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 2017 / 0112111 [Non-patent literature]

[0007] [Non-Patent Document 1] Nikolic, MS et al., 2001, “Synthesis and characterization of biodegradable poly(butylene succinate-co-butylene adipate)s” [Non-patent document 2] Qi, J. et al., 2019, “An investigation of the thermal and (bio)degradability of PBS copolyesters based on isosorbide” Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for producing a biodegradable polyester in which discoloration is effectively suppressed. The purpose is to provide.

[0009] Another object of the present invention is to provide a biodegradable food product which is produced by the above-mentioned production method and in which discoloration is effectively suppressed. The object of the present invention is to provide a highly flexible polyester. [Means for solving the problem]

[0010] According to one embodiment of the present invention, (1) (a) an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid (b) a dicarboxylic acid component containing a short aliphatic diol having a chain length of less than 4 carbon atoms; (c) a reaction mixture containing the ol component and a discoloration inhibitor in the presence of all or a portion of a catalyst; a step of carrying out an esterification reaction or a transesterification reaction to obtain a prepolymer; 2) The prepolymer obtained in step (1) is mixed with a stabilizer and the remaining part of the catalyst. and a step of subjecting the resulting mixture to a condensation polymerization reaction under a temperature of 1000° C. or without an additional catalyst to obtain a biodegradable polyester. The discoloration inhibitor contains a compound represented by the following chemical formula 1 in a total molar ratio of the dicarboxylic acid component (a). When Y is hydrogen or a methyl group, the content is 1.5 mol % to 3.5 mol % based on the number of atoms. When Y is a hydroxy group, the content is 1.0 mol % to 2.0 mol %, and the biodegradable polymer When the polyester is measured at 190°C with a load of 2.16 kg, the melting point is 100 g / 10 min or less. It has a melt flow index, color characteristics L* of 60 or more, a* and a* and b* are each 8 or less, Provided.

[0011] [ka] In the formula, m, n, and l≧1, k≧0, and Y is hydrogen, a hydroxyl group, or is a methyl group.

[0012] In an embodiment of the present invention, the aromatic dicarboxylic acid is terephthalic acid, isophthalic acid, ol Sophthalic acid, naphthalenedicarboxylic acid, dimethyl terephthalate, dimethyl isophthalate dimethyl phthalate, and dimethyl naphthalenedicarboxylic acid. It may include at least one of:

[0013] In an embodiment of the present invention, the aliphatic dicarboxylic acid is oxalic acid, malonic acid, succinic acid, glycerol, hydroxybenzoic acid ... Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and The compound may contain at least one selected from the group consisting of the ester compounds:

[0014] In a preferred embodiment of the present invention, the aromatic dicarboxylic acid comprises terephthalic acid and the aliphatic The dicarboxylic acid may include adipic acid.

[0015] In an embodiment of the present invention, the content of aromatic dicarboxylic acid is determined based on the total moles of the dicarboxylic acid component. The content of aliphatic dicarboxylic acid is 20 mol % to 60 mol % based on the number of dicarboxylic acids. The amount may be 40 mol % to 80 mol % based on the total number of moles of the phosphoric acid components.

[0016] In an embodiment of the present invention, the diol component (b) is ethylene glycol, 1,2-propanol, at least one selected from the group consisting of 1,3-propanediol, and 1,3-propanediol; It may include one.

[0017] In a preferred embodiment of the present invention, the diol component (b) may comprise ethylene glycol. do.

[0018] In an embodiment of the present invention, the molar ratio of diol component (b) to dicarboxylic acid component (a) is 1 It can be 1:1 to 1.5:1.

[0019] In an embodiment of the present invention, the compound represented by Formula 1 is a compound selected from the group consisting of glycerol, trimethylol, and at least one selected from the group consisting of diethylpropane and pentaerythritol. obtain.

[0020] In an embodiment of the present invention, the catalyst is tetrabutyl titanate, tetraisopropyl titanate, at least one selected from the group consisting of zinc nitrate, zinc acetate, and antimony oxide; The content of the catalyst may be 0.01 g to 5 g based on 1 mole of the dicarboxylic acid component (a). It can be .0g.

[0021] In an embodiment of the present invention, the stabilizer is selected from the group consisting of phosphorous acid, triphenyl phosphate, and triethylphosphonoacetate, The content of the stabilizer is 0.01 g to 5.0 g based on 1 mole of the dicarboxylic acid component (a). could be.

[0022] In an embodiment of the present invention, the esterification or transesterification reaction of the reaction mixture is carried out by The reaction may be carried out in one reactor at different temperatures, and the primary esterification or transesterification may be carried out in the same reactor. The esterification reaction is carried out at a temperature in the range of 180°C to 200°C, and secondary esterification or The transesterification reaction may be carried out at a temperature ranging from 220°C to 235°C.

[0023] In an embodiment of the present invention, the condensation polymerization reaction of the prepolymer is carried out at a temperature ranging from 220°C to 235°C. The heating may be performed at a vacuum of less than 1 torr for 60 to 420 minutes.

[0024] According to another embodiment of the present invention, an aliphatic dicarboxylic acid and Dicarboxylic acid residues derived from aromatic dicarboxylic acids and short chains with less than 4 carbon atoms It contains diol residues derived from aliphatic diols and is soluble in water at 190°C under a load of 2.16 kg. When measured, it has a melt flow index of 100 g / 10 min or less and a color characteristic L* of 60 Thus, a biodegradable polyester in which each of a* and b* is 8 or less is provided.

[0025] In an embodiment of the present invention, the biodegradable polyester is a disposable film or sheet, It may be used for an application selected from the group consisting of tableware, agricultural films or sheets. [Effects of the Invention]

[0026] The method for producing biodegradable polyester according to one embodiment of the present invention effectively suppresses discoloration. It is possible to provide a biodegradable polyester.

[0027] Furthermore, discoloration of the biodegradable polyester produced by the above-mentioned production method is effectively suppressed. It can be used in a variety of fields. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will now be described in more detail.

[0029] According to one embodiment of the present invention, (1) (a) an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid (b) a dicarboxylic acid component containing a short aliphatic diol with a chain length of less than 4 carbon atoms; and (c) a reaction mixture containing a discoloration inhibitor in the presence of all or a portion of a catalyst. a step of carrying out an esterification reaction or a transesterification reaction to obtain a prepolymer; 2) The prepolymer obtained in step (1) is reacted with a stabilizer and the remaining part of the catalyst. and subjecting the resulting mixture to a condensation polymerization reaction with or without an additional catalyst to obtain a biodegradable polyester. A method for producing biodegradable polyester is provided.

[0030] [Step (1)] In step (1) of the method for producing biodegradable polyester according to the embodiment of the present invention, (a) (b) a dicarboxylic acid component containing an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid; (c) a diol component containing a short aliphatic diol having less than 4 carbon atoms; and (c) a discoloration inhibitor. The reaction mixture is subjected to an esterification or transesterification reaction in the presence of all or a portion of a catalyst. The prepolymer is obtained by a polymerization reaction.

[0031] In the step (1), the reaction mixture is a mixture of (a) an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. (b) a dicarboxylic acid component containing a short aliphatic diol having a chain length of less than 4 carbon atoms; and (c) a discoloration inhibitor.

[0032] In an embodiment of the present invention, one component of the reaction mixture, dicarboxylic acid component (a), is an aromatic The aromatic dicarboxylic acids include aromatic dicarboxylic acids and aliphatic dicarboxylic acids. The aliphatic dicarboxylic acid may include an ester compound thereof. Ester compounds of carboxylic acids are compounds in which the hydrogen atoms at both ends of the dicarboxylic acid are alkyl groups with 1 to 6 carbon atoms. It may refer to a substituted ester compound.

[0033] In an embodiment of the present invention, the aromatic dicarboxylic acid is terephthalic acid, isophthalic acid, ol Sophthalic acid, naphthalenedicarboxylic acid, dimethyl terephthalate, dimethyl isophthalate dimethyl phthalate, and dimethyl naphthalenedicarboxylic acid. The present invention is not limited to the above. In a preferred embodiment, the aromatic dicarboxylic acid may include terephthalic acid.

[0034] In an embodiment of the present invention, the aliphatic dicarboxylic acid is oxalic acid, malonic acid, succinic acid, glycerol, hydroxybenzoic acid ... Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and The compound may contain at least one selected from the group consisting of the ester compounds of In a preferred embodiment of the present invention, the aliphatic dicarboxylic acid is azide. It may contain pinic acid.

[0035] In a preferred embodiment of the present invention, the aromatic dicarboxylic acid comprises terephthalic acid and the aliphatic The dicarboxylic acid may include adipic acid.

[0036] In an embodiment of the present invention, the content of aromatic dicarboxylic acid is determined based on the total moles of the dicarboxylic acid component. The content of aromatic dicarboxylic acid is preferably 20 mol % to 60 mol % based on the number of aromatic dicarboxylic acids. The amount may be 40 mol % to 60 mol % based on the total number of moles of the dicarboxylic acid components.

[0037] In an embodiment of the present invention, the content of aliphatic dicarboxylic acids is The content of aliphatic dicarboxylic acids is preferably 40 mol % to 80 mol % based on the number of the dicarboxylic acids. The amount may be 40 mol % to 60 mol % based on the total number of moles of the dicarboxylic acid components.

[0038] The content of aromatic dicarboxylic acid is more than 60 mol% based on the total number of moles of dicarboxylic acid components. If the amount of fat is too high, the biodegradability of the resulting biodegradable polyester may decrease. When the content of aromatic dicarboxylic acid exceeds 80 mol % based on the total number of moles of dicarboxylic acid components, However, the mechanical properties of the resulting biodegradable polyester may be reduced.

[0039] In an embodiment of the present invention, the other component of the reaction mixture, diol component (b), is The diols include short aliphatic diols having less than 4 carbon atoms.

[0040] In an embodiment of the present invention, the diol component (b) is ethylene glycol, 1,2-propanol, at least one selected from the group consisting of 1,3-propanediol, and 1,3-propanediol; In a preferred embodiment of the present invention, the diol component (b) may comprise ethylene glycol. It may include a call.

[0041] In an embodiment of the present invention, the molar ratio of diol component (b) to dicarboxylic acid component (a) is: The molar ratio can be 1.1:1 to 1.5:1. The smaller this molar ratio, the more advantageous it is from an economical standpoint. However, if it is too small, the polymerization rate may decrease due to an imbalance in the equivalent ratio of diol and dicarboxylic acid. do.

[0042] In the step (1), the reaction mixture contains a discoloration inhibitor (c). It is preferred that the discoloration inhibitor be included in the reaction mixture, but it is also preferred that the discoloration inhibitor be included in the esterification reaction or the transesterification reaction. The present invention excludes the separate addition of the compound during the esterification reaction or the polycondensation reaction. It is not something that can be done.

[0043] In an embodiment of the present invention, the discoloration inhibitor may include a compound represented by the following Chemical Formula 1:

[0044] [ka] In the formula, m, n, and l≧1, k≧0, and Y is hydrogen, a hydroxyl group, or is a methyl group.

[0045] In an embodiment of the present invention, the compound represented by Formula 1 is a compound selected from the group consisting of glycerol, trimethylol, and at least one selected from the group consisting of diethylpropane and pentaerythritol. However, it is not particularly limited to these.

[0046] The compound represented by the above-mentioned Chemical Formula 1 is a compound that is branched in three or more directions during the production of polyester. It is known as a branching agent because it can form structures, mainly polyester branching. Increases molecular weight and shear thinning effect It is used as a means to improve

[0047] In the present invention, the compound represented by Chemical Formula 1 is a short chain having less than 4 carbon atoms. In order to solve the discoloration phenomenon that can occur during polyester production, a new aliphatic diol is used. It acts as a discoloration inhibitor.

[0048] Discoloration problem during the production of polyester using a short aliphatic diol with a chain length of less than 4 carbon atoms The subject is the formation of an ester bond between an aliphatic diol and an aliphatic dicarboxylic acid by a thermal side reaction or This may be due to a change in the chemical structure caused by depolymerization. enkatachalam, S. et al., 2012, “Degradat ion and recyclability of Poly (Ethylene As reported in "Polyethylene terephthalate" The discoloration of the polymer is due to the long chain conjugate diene caused by β-scission of the main chain. This is understood to be due to the formation of conjugated dienes.

[0049] Incidentally, the temperature of the polycondensation reaction in the present invention is the same as that in the case of polyethylene terephthalate ( Since the temperature range is 220 to 235°C, which is lower than the range of 260°C or higher, it is possible to The ester bond between aliphatic diol and aliphatic dicarboxylic acid is more preferable than the ester bond between aliphatic diol and aliphatic dicarboxylic acid. It is believed that the substance that causes discoloration was generated from the ester bond between the two. The compound to be treated is an ester bond between such an aliphatic diol and an aliphatic dicarboxylic acid. It is understood that this inhibits the decomposition of

[0050] The compound represented by chemical formula 1 is a compound in which, when Y is hydrogen or a methyl group, the dicarboxylic acid component (a It can be used in a content of 1.5 mol % to 3.5 mol % based on the total number of moles of polyester. In order to more effectively inhibit discoloration of the ether, the compound represented by Chemical Formula 1 is When is a methyl group, it is 1.6 mol % to 2.5 mol % based on the total number of moles of the dicarboxylic acid component (a). It is preferred to use it in a molar percentage content.

[0051] The compound represented by chemical formula 1 is a compound in which the content of Y is a dicarbazole or methyl group. If the total number of moles of the carboxylic acid component (a) is less than 1.5 mol %, after the start of the condensation polymerization reaction, Discoloration of the reactants can occur rapidly within minutes, and if the content exceeds 3.5 mol % , the reaction may gel.

[0052] In addition, when Y is a hydroxy group, the compound represented by Chemical Formula 1 has a dicarboxylic acid component (a It can be used in a content of 1.0 mol% to 2.0 mol% based on the total number of moles of polyester. In order to more effectively inhibit discoloration of the resin, the compound represented by formula 1 is group, 1.1 mol % to 1.5 mol % based on the total number of moles of the dicarboxylic acid component (a). It is preferred to use it in the amount of

[0053] In the compound represented by chemical formula 1, when Y is a hydroxy group, the content is a dicarboxylic acid compound. When the total number of moles of component (a) is less than 1.0 mol %, the polymerization reaction If the content exceeds 2.0 mol%, the reaction may rapidly discolor. Things can gel.

[0054] In the step (1), the reaction mixture is subjected to esterification in the presence of all or a part of a catalyst. The prepolymer is obtained by reaction or transesterification.

[0055] In an embodiment of the present invention, the catalyst is tetrabutyl titanate, tetraisopropyl titanate, at least one selected from the group consisting of zinc nitrate, zinc acetate, and antimony oxide; These may include, but are not limited to:

[0056] The catalyst is used in an amount of 0.01 g to 5.0 g based on 1 mole of the dicarboxylic acid component (a). Preferably, the catalyst is used in an amount of 0.1 g to 1 mole of the dicarboxylic acid component (a). It can be used at a content of 1.0 g.

[0057] In the step (1), the reaction mixture is subjected to an esterification reaction or A transesterification reaction can be carried out to obtain a prepolymer without the need for an additional catalyst. The catalyst remaining in the prepolymer can be used in the polycondensation reaction described below. The mixture is subjected to an esterification or transesterification reaction in the presence of a portion of a catalyst to A prepolymer is obtained. In this case, the prepolymer is polycondensed in the presence of the remaining part of the catalyst. Can react.

[0058] In an embodiment of the present invention, the esterification or transesterification reaction of the reaction mixture is carried out by Different temperature ranges can be used in the same reactor. For example, primary esterification or transesterification can be used. The transesterification reaction is carried out at a temperature in the range of 180°C to 200°C for 60 to 90 minutes. The dicarboxylic acid and the aliphatic diol are allowed to undergo a condensation reaction to form an oligomer. The secondary esterification or transesterification reaction is carried out at temperatures ranging from 220°C to 235°C. The reaction is carried out for 0 to 90 minutes to form a polyester prepolymer.

[0059] [Step (2)] In step (2) of the method for producing biodegradable polyester according to the embodiment of the present invention, The prepolymer obtained in 1) is reacted in the presence of a stabilizer and the remaining part of the catalyst, or Biodegradable polyester is obtained by polycondensation reaction without the use of an additional catalyst.

[0060] In an embodiment of the present invention, the stabilizer is selected from the group consisting of phosphorous acid, triphenyl phosphate, and triethylphosphonoacetate, There is no particular limitation to these.

[0061] The stabilizer is contained in an amount of 0.01 g to 5.0 g based on 1 mole of the dicarboxylic acid component (a). Preferably, the stabilizer is used in an amount of 0.01 mole based on 1 mole of the dicarboxylic acid component (a). It can be used at a content of 0.1g to 4.0g.

[0062] In an embodiment of the present invention, the stabilizer is used in step (2), but a portion of it is used in step (1). ) may also be used.

[0063] The details of the catalyst are as described in the step (1).

[0064] In the step (2), the degree of polymerization of the prepolymer can be increased by a polycondensation reaction. The polymerization reaction is carried out at a temperature ranging from 220°C to 235°C, at a vacuum of less than 1 torr, for 60 minutes to 420 minutes. In this case, if the temperature of the polycondensation reaction exceeds 235°C, the aliphatic-aromatic poly Esters can rapidly discolor within a few minutes, so they should be stored in a temperature range of 220°C to 230°C. It is preferable that the reaction proceeds in the following manner.

[0065] The biodegradable polyester obtained in step (2) was found to be soluble in water at 190°C under a load of 2.16 kg. When measured, it has a melt flow index of 100 g / 10 min or less and a color characteristic L* of 60 As mentioned above, each of a* and b* can be 8 or less.

[0066] According to another embodiment of the present invention, a 2.16kJ / cm2 ceramic capacitor is manufactured by the above manufacturing method and has a temperature of 190°C. When measured with a g load, it has a melt flow index of 100 g / 10 min or less and a color characteristic of L a* is 60 or more, and a* and b* are each 8 or less. can be.

[0067] The biodegradable polyester according to the present invention is a mixture of aliphatic dicarboxylic acids and aromatic dicarboxylic acids. Dicarboxylic acid residues derived from carboxylic acids and short aliphatic chains with less than 4 carbon atoms It may contain diol residues derived from diols.

[0068] The aliphatic-aromatic polyester according to one embodiment of the present invention meets the international standard for biodegradability assessment, IS It is biodegradable under test conditions according to O 14855-1.

[0069] The biodegradable polyester according to the present invention is a polymer that is similar to the existing poly(butylene adipate-c Disposable films or sheets, tableware, agricultural filters, etc. that use o-terephthalate It can be applied to various fields of daily life such as furniture, seats, etc. [Example]

[0070] The present invention will be described in more detail below with reference to examples and comparative examples. These are merely illustrative of the present invention and are not intended to limit the scope of the present invention. It's not that.

[0071] Example 1 A reactor equipped with a condenser was charged with 1.61 moles of ethylene glycol, adipic acid, and 0.60 mol of terephthalic acid and 0.55 mol of tetrabutyl titanate were added to the mixture. 0.3g of glycerol and 1.72g of glycerol were added, and the primary esterification was carried out at 190°C for 60 minutes. The reactor temperature was then raised to 230°C and the secondary esterification reaction was carried out for 90 minutes. went.

[0072] Next, 0.27 g of tetrabutyl titanate and 0.05 g of phosphorous acid were added to the prepolymer. The resulting mixture was subjected to a polycondensation reaction at 230°C under a vacuum of less than 1 torr for 150 minutes. An aromatic polyester was obtained.

[0073] Example 2 The same procedure as in Example 1 was carried out, except that the amount of glycerol was changed to 2.30 g. Aliphatic-aromatic polyesters were obtained.

[0074] Example 3 As a discoloration inhibitor, 2.30 g of pentaerythritol was used instead of glycerol. The aliphatic-aromatic copolymer was prepared in the same manner as in Example 1, except that the polycondensation reaction was carried out for 180 minutes. The aromatic polyester was obtained.

[0075] (Comparative Example 1) Except that the amount of glycerol was changed to 1.15 g and the polycondensation reaction was carried out for 240 min. The reaction was carried out in the same manner as in Example 1 to obtain an aliphatic-aromatic polyester.

[0076] (Comparative Example 2) As a discoloration inhibitor, 3.45g of pentaerythritol was used instead of glycerol. The reaction was carried out in the same manner as in Example 1, except that the polycondensation reaction was carried out for 60 minutes. Aromatic-aromatic polyesters were obtained.

[0077] (Comparative Example 3) As a discoloration inhibitor, 1.15g of pentaerythritol was used instead of glycerol. The aliphatic-aromatic copolymer was prepared in the same manner as in Example 1, except that the polycondensation reaction was carried out for 240 minutes. The aromatic polyester was obtained.

[0078] Comparative Example 4 As a discoloration inhibitor, 0.57g of pentaerythritol was used instead of glycerol. The aliphatic-aromatic copolymer was prepared in the same manner as in Example 1, except that the polycondensation reaction was carried out for 240 minutes. The aromatic polyester was obtained.

[0079] (Comparative Example 5) The same procedure as in Example 1 was carried out except that the polycondensation reaction was carried out for 240 minutes without using the discoloration inhibitor. Aliphatic-aromatic polyesters were obtained by this method.

[0080] The polymerization conditions for the above examples and comparative examples are summarized in Table 1 below.

[0081] [Table 1]

[0082] (Test example) The aliphatic-aromatic polyesters obtained in the above examples and comparative examples were tested by the following methods. The results are shown in Table 2 below.

[0083] (1) Melt flow index (MFI) Aliphatic-aromatic at 190°C with a 2.16 kg load based on ASTM D1238 The melt flow index of polyester was measured. If the melt flow index exceeds 200 g / 10 min. The measurement error was set at ±10%, and approximate values ​​are shown in the table.

[0084] (2) Color characteristics Spectrophotometer (spectrophotometer SE 7700, Nippon Denshoku Kogyo Co., Ltd.) ) was used to measure the color properties of aliphatic-aromatic polyesters.

[0085] (3) Gel 1 g of aliphatic-aromatic polyester was completely dissolved in 50 ml of chloroform solvent. The presence or absence of gel in the product can be determined by the presence or absence of gel when filtered through a stainless steel mesh (60 mesh). confirmed.

[0086] [Table 2]

[0087] As can be seen from Tables 1 and 2, the compound of Formula 1 was used in Examples 1 to 3. Comparing Examples 1 and 3 to 5, the color characteristic L* value is high in the Examples, and a The values ​​of * and b* are shown to be close to zero. Also, measurements are taken at 190°C with a load of 2.16 kg. The melt flow index at that time was less than 100 g / 10 min.

[0088] On the other hand, in Comparative Example 2, in which the compound of Formula 1 was used in an amount exceeding the range of the present invention, The color properties were excellent, but gelation occurred.

Claims

1. (1) A step of subjecting a dicarboxylic acid component (a) containing an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid, a diol component (b) containing a short aliphatic diol having a chain length of less than 4 carbon atoms, and a reaction mixture (c) containing a discoloration inhibitor to an esterification reaction or transesterification reaction in the presence of all or a portion of a catalyst to obtain a prepolymer; (2) subjecting the prepolymer obtained in step (1) to a condensation polymerization reaction in the presence of a stabilizer and the remaining portion of the catalyst, or in the absence of additional catalyst, to obtain a biodegradable polyester; 1. A method for producing a biodegradable polyester, wherein the discoloration inhibitor contains a compound represented by the following chemical formula 1 in a content of 1.5 mol % to 3.5 mol % when Y is hydrogen or a methyl group, and in a content of 1.0 mol % to 2.0 mol % when Y is a hydroxy group, based on the total number of moles of the dicarboxylic acid component (a); and the biodegradable polyester has a melt flow index of 100 g / 10 min or less when measured at 190° C. under a load of 2.16 kg, a color property L* of 60 or more, and each of a* and b* of 8 or less: 【Chemistry 1】 In Formula 1, m≧0, n and l≧1, k≧0, and Y is hydrogen, a hydroxyl group, or a methyl group.

2. 2. The method for producing biodegradable polyester according to claim 1, wherein the aromatic dicarboxylic acid comprises at least one selected from the group consisting of terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, dimethyl terephthalate, dimethyl isophthalate, dimethyl phthalate, and dimethyl naphthalenedicarboxylic acid.

3. 2. The method for producing biodegradable polyester according to claim 1, wherein the aliphatic dicarboxylic acid includes at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and ester compounds thereof.

4. The aromatic dicarboxylic acid includes terephthalic acid, The method for producing biodegradable polyester according to claim 1 , wherein the aliphatic dicarboxylic acid includes adipic acid.

5. the content of the aromatic dicarboxylic acid is 20 mol % to 60 mol % based on the total number of moles of the dicarboxylic acid component (a), The method for producing biodegradable polyester according to claim 1, wherein the content of the aliphatic dicarboxylic acid is 40 mol% to 80 mol% based on the total number of moles of the dicarboxylic acid component (a).

6. 2. The method for producing biodegradable polyester according to claim 1, wherein the diol component (b) includes at least one selected from the group consisting of ethylene glycol, 1,2-propanediol, and 1,3-propanediol.

7. The method for producing biodegradable polyester according to claim 6 , wherein the diol component (b) contains ethylene glycol.

8. 2. The method for producing biodegradable polyester according to claim 1, wherein the molar ratio of the diol component (b) to the dicarboxylic acid component (a) is 1.1:1 to 1.5:

1.

9. 2. The method for producing biodegradable polyester according to claim 1, wherein the compound represented by Chemical Formula 1 includes at least one selected from the group consisting of glycerol, trimethylolpropane, and pentaerythritol.

10. the catalyst comprises at least one selected from the group consisting of tetrabutyl titanate, tetraisopropyl titanate, zinc acetate, and antimony oxide; The method for producing biodegradable polyester according to claim 1, wherein the content of the catalyst is 0.01 g to 5.0 g based on 1 mole of the dicarboxylic acid component (a).

11. The method for producing biodegradable polyester according to claim 1, wherein the esterification or transesterification of the reaction mixture (c) is carried out in one reactor at different temperature ranges, with the primary esterification or transesterification reaction being carried out at a temperature in the range of 180°C to 200°C and the secondary esterification or transesterification reaction being carried out at a temperature in the range of 220°C to 235°C.

12. the stabilizer comprises at least one selected from the group consisting of phosphorous acid, triphenyl phosphate, and triethyl phosphonoacetate; The method for producing biodegradable polyester according to claim 1, wherein the content of the stabilizer is 0.01 g to 5.0 g based on 1 mole of the dicarboxylic acid component (a).

13. 2. The method for producing biodegradable polyester according to claim 1, wherein the polycondensation reaction of the prepolymer is carried out at a temperature in the range of 220°C to 235°C under a vacuum of less than 1 torr for 60 to 420 minutes.

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