Biodegradable polyester resins prepared by adding a reaction rate controller and a molecular weight increasing agent derived from biomass and a method for preparing the same

Abstract

The present invention relates to a biodegradable polyester resin prepared by adding a reaction rate controlling agent and a molecular weight increasing agent derived from biomass; and a method for preparing the same, and more particularly to a biodegradable polyester resin and a method for preparing the same, in which, in order to obtain a biodegradable polyester resin having a reaction rate, flexibility, and tensile strength superior to those of polybutylene-co-adipate terephthalate, a biodegradable polyester resin, a polyglycerol succinate having a number average molecular weight of 500 to 1,000, which is synthesized through an esterification reaction between glycerol and succinic acid, is added as a reaction rate controlling agent derived from biomass to increase the reaction rate in the synthesis of the biodegradable polyester resin, and a polyglycerol furanic acid ester having a number average molecular weight of 1,000 to 5,000, which is synthesized through an esterification reaction between glycerol and 2,5-furandicarboxylic acid, is added as a molecular weight increasing agent derived from biomass to increase the tensile strength, thereby preparing a biodegradable polyester resin having a number average molecular weight of 70,000 or more, a weight average molecular weight of 150,000 or more, an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, and a tensile strength of 400 kgf / cm 2 The biodegradable polyester resin above.

Description

Technical Field

[0001] This invention relates to: biodegradable polyester resins prepared by adding biomass-derived reaction rate controllers and molecular weight increasers; and methods for preparing the same; more specifically, to biodegradable polyester resins and methods for preparing the same, wherein, in order to obtain a biodegradable polyester resin having a reaction rate, flexibility, and tensile strength superior to polybutene-co-adipate terephthalate (a conventional biodegradable polyester resin), polyglycerol succinate with a number-average molecular weight of 500 to 1,000, synthesized via an esterification reaction between glycerol and succinic acid, is used as a biomass-derived... A reaction rate control agent is added to increase the reaction rate in the synthesis of biodegradable polyester resins. Polyglycerol furanoates with a number average molecular weight of 1,000 to 5,000, synthesized via esterification of glycerol and 2,5-furandicarboxylic acid, are added as biomass-derived molecular weight increasers to increase tensile strength. This results in the preparation of resins with a number average molecular weight of 70,000 or higher, a weight average molecular weight of 150,000 or higher, an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, and a tensile strength of 400 kgf / cm². 2 The above are biodegradable polyester resins. Background Technology

[0002] As living environments become more prosperous and affluent, the use of single-use plastics is gradually increasing. Single-use plastics used in this way cause serious environmental pollution when disposed of in the natural environment.

[0003] Therefore, in order to address these issues, numerous studies are currently being conducted worldwide to overcome these serious environmental problems by manufacturing disposable products using biodegradable resins.

[0004] Biodegradable compositions have been known for decades. That is, aromatic / aliphatic copolyester resins are reacted with aromatic dicarboxylic acids (such as terephthalic acid and dimethyl terephthalate), aliphatic dicarboxylic acids (such as adipic acid), and diols (such as 1,4-butanediol) to prepare polybutene-co-adipate terephthalate, and the prepared polybutene-co-adipate terephthalate is currently produced worldwide by KINGFA, BASF, Novamont, Tunhe, Jinhui, S-EnPol, Xingfu, and Soltech, and has been available for sale for decades.

[0005] All these companies use nearly constant amounts of raw materials and the same raw materials, such as terephthalic acid, adipic acid, and 1,4-butanediol. However, the physical properties of the products from all these companies vary, depending on the process conditions used to manufacture polybutene-co-adipate terephthalate.

[0006] When describing prior art related to currently developed biodegradable resins, Korean Patent Registration No. 10-0129794 (November 13, 1997) discloses a method for obtaining an aliphatic polyester resin with a number average molecular weight of about 15,000 to 20,000 in the presence of a ternary or more polyol monomer or a ternary or more polycarboxylic acid monomer as a reaction auxiliary component, and then obtaining an aliphatic polyester resin with a number average molecular weight of about 20,000 to 70,000 by further reacting it with isocyanate as a coupling agent. According to this method, due to the long reaction time, low productivity, and unsuitability for membranes, and because the isocyanate used as a coupling agent to increase the molecular weight is extremely harmful to human health, there is a need for work safety precautions.

[0007] Furthermore, in Korean Patent Registration No. 10-198045, there are issues that are not understood by those skilled in the art: the high acid value after the polycondensation reaction used to prepare polybutene-co-adipate terephthalate is reduced due to solid-state polymerization; the chemical formula obtained from the reaction of DL-malic acid with 1,4-cyclohexanediethanol is incorrect, and unreacted 1,4-cyclohexanediethanol remains, thus slowing down the reaction rate; and the four preparation steps implemented through the reaction of the polycondensation compound with the ester and solid-state polymerization raise questions about economic feasibility and effectiveness, as this preparation process is completed in two steps by other manufacturers. In addition, solid-state polymerization after polycondensation cannot reduce the acid value; the heat distortion temperature of polybutene-co-adipate terephthalate is 70°C to 80°C, but solid-state polymerization cannot occur at 100°C.

[0008] Furthermore, in Korean Patent Publication No. 1997-0707206, a method for preparing aliphatic / aromatic copolyesters uses adipic acid and succinic acid as aliphatic dicarboxylic acids, terephthalic acid as an aromatic dicarboxylic acid, and dimethyl terephthalate and 1,4-butanediol as aliphatic diols, to prepare aliphatic / aromatic copolyester copolymers via polycondensation. To increase the molecular weight, trifunctional monomers, isocyanates, and sulfonates are added. However, this preparation involves reaction time, gelation, etc., and even after this synthesis, the number-average molecular weight (Mn) is approximately 1,000 to 5,000, which may degrade tensile strength and quality.

[0009] Furthermore, Korean Patent Registration No. 10-428687 (April 12, 2004) discloses a method for preparing a biodegradable resin composition, which is prepared by compounding 3 to 65 parts by weight of polylactic acid relative to 100 parts by weight of an aliphatic polyester and an aliphatic / aromatic copolyester using a twin-screw extruder. In this case, a problem exists in the compounding process of polylactic acid (or its copolymers) and polybutylene succinate (or its copolymers), because of the high melting point of polylactic acid, the thermal stability of the resin prepared during high-temperature extrusion is significantly reduced, and the mechanical properties of the prepared resin are also reduced.

[0010] In addition, in US 4,328,059 (May 4, 1982) and US 4,094,721 (June 13, 1980), terephthalic acid was used as an aromatic dicarboxylic acid, adipic acid was used as an aliphatic dicarboxylic acid, and 1,4-butanediol was used as a diol component to prepare polybutene-co-adipate terephthalate.

[0011] Furthermore, in Korean Patent Registration No. 10-1200824, polybutene-co-adipate terephthalate, i.e., aromatic / aliphatic copolyester resin, is prepared using unsaturated compounds, etc. If the unsaturated compounds, etc., are not properly adjusted, gelation problems will occur.

[0012] Therefore, existing biodegradable resins (polybutene-co-adipate terephthalate) have been known for decades, and their physical properties vary depending on who prepares the polybutene-co-adipate terephthalate with good physical properties and by what method. However, existing methods face difficulties in widespread use due to poor tensile strength and transparency, and their use is limited compared to existing non-biodegradable resins due to poorer processability.

[0013] Therefore, since the raw materials used to prepare polybutene-co-adipate terephthalate (i.e., aromatic / aliphatic copolyester) have been known for decades, the key is to improve the physical properties by using a third material to create fully biodegradable single-use biodegradable products, thereby solving the environmental pollution problem, by improving processability, transparency and tensile strength (which are problems with existing biodegradable resins).

[0014] Therefore, the inventors developed a biodegradable polyester resin using an aromatic / aliphatic copolyester with excellent reaction rate and tensile strength, exhibiting an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, a number-average molecular weight of over 70,000, and a tensile strength of 400 kgf / cm. 2The present invention is achieved by using the above-mentioned biodegradable polyester resin and simultaneously maximizing yield and solving problems related to biodegradability (such as flexibility, tensile strength and durability) by freely controlling the reaction rate (that is, the polycondensation time compared with existing biodegradable resins).

[0015] Public content

[0016] Technical issues

[0017] One object of the present invention is to provide a biodegradable polyester resin having excellent flexibility and tensile strength and being completely degradable when disposed of in the natural environment, and to provide a method for preparing the biodegradable polyester resin to protect the natural environment, the method being achieved by solving the problems of reaction rate, tensile strength and durability (which are problems of existing biodegradable polyester resins) and processability (which is a disadvantage of existing biodegradable polyester resins).

[0018] Specifically, one object of the present invention is to provide a biodegradable polyester resin and a method for preparing the same, wherein, in order to obtain a biodegradable polyester resin having a better reaction rate, flexibility, and tensile strength than polybutene-co-adipate terephthalate (a conventional biodegradable polyester resin), a polyglycerol succinate with a number-average molecular weight of 500 to 1,000, synthesized by esterification between glycerol and succinic acid, is added as a biomass-derived reaction rate control agent to increase the reaction rate in the synthesis of the biodegradable polyester resin; and a polyglycerol furanate with a number-average molecular weight of 1,000 to 5,000, synthesized by esterification between glycerol and 2,5-furandicarboxylic acid, is added as a biomass-derived molecular weight increaser to increase tensile strength, thereby preparing a resin with a number-average molecular weight of 70,000 or more, a weight-average molecular weight of 150,000 or more, an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, and a tensile strength of 400 kgf / cm². 2 The above are biodegradable polyester resins.

[0019] Technical solution

[0020] To address this problem, the present invention provides a biodegradable polyester resin exhibiting excellent reaction rate, tensile strength, and durability, and possessing an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, a number-average molecular weight of over 70,000, a weight-average molecular weight of over 150,000, and a molecular weight of over 400 kgf / cm³. 2 The above tensile strength.

[0021] More specifically, the present invention provides a method for preparing a biodegradable polyester resin with excellent flexibility and durability for use in disposable products and plastic articles made of biodegradable resin, wherein 1,4-butanediol can be used as a diol component.

[0022] In addition, aliphatic (including cyclic aliphatic) dicarboxylic acids (or anhydrides) include succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid and their anhydrides, but these aliphatic (including cyclic aliphatic) dicarboxylic acids or their anhydrides may be used alone or as a mixture of two or more of them.

[0023] As another preferred specific example, in the method for preparing the aliphatic / aromatic copolyester polymer of the present invention, the weight ratio of aromatic dicarboxylic acid to aliphatic dicarboxylic acid in the acid component is preferably 40:60 to 60:40. In this case, in order to have biodegradability, if the aromatic content of the total acid component exceeds 55% by weight, it will not be biodegradable, so this needs to be noted.

[0024] In addition, this technical solution involves adding polyglycerol succinate with a number average molecular weight of 500 to 1,000, which is synthesized through an esterification reaction between glycerol and succinic acid derived from biomass, as a reaction rate control agent derived from biomass during the synthesis of the biodegradable polyester resin of the present invention.

[0025] In other words, as a reaction rate control agent according to the present invention, polyglycerol succinate is used by directly synthesizing polyglycerol succinate with a molecular weight of 500 to 1,000 according to the following reaction formula 1, which is obtained by esterification reaction between glycerol derived from biomass and succinic acid, followed by polycondensation reaction.

[0026] [Reaction Formula 1]

[0027] .

[0028] In addition, this technical solution involves adding polyglycerol furanoate with a number average molecular weight of 2,000 to 5,000, prepared by synthesizing glycerol and 2,5-furandicarboxylic acid derived from biomass, as a biomass-derived molecular weight increaser during the synthesis of biodegradable polyester resin, in order to increase the tensile strength of the biodegradable polyester resin of the present invention.

[0029] In other words, as a molecular weight increaser according to the present invention, polyglycerol furanoate is used by directly synthesizing polyglycerol furanoate with a molecular weight of 2,000 to 5,000 according to the following reaction formula 2, which is obtained by an esterification reaction between glycerol derived from biomass and 2,5-furandicarboxylic acid, followed by a polycondensation reaction.

[0030] [Reaction 2]

[0031] .

[0032] Furthermore, as another preferred specific example, at the beginning or end of the esterification, transesterification and polycondensation reactions for synthesizing the biodegradable polyester resin of the present invention, the catalyst to be added is used in the range of 0.01% to 0.8% by weight based on the total weight of the reactants.

[0033] As a specific example of a catalyst mentioned in the known [cited in Sax Toxi Substance Data Book Fujiyama, Maruzer.k.k360s, EP-A 565,235] Roempo Chemie Lexikon, Vol. 6, Thieme Verlag, Stuttgart, New York, 9th edition [1992, pp. 4626-4633], the catalyst preferably uses one or a mixture of two or more selected from the group consisting of tetrabutyl titanate, trioctyl antimony oxide, tin oxide, calcium acetate, zinc acetate, tetrapropyl titanate, etc.

[0034] As another preferred specific example, a stabilizer is further added at the beginning or end of the esterification reaction, transesterification reaction, and polycondensation reaction.

[0035] As a stabilizer disclosed in known EP application No. 13,461 and U.S. application No. 4,328,049, the stabilizer is used in the range of 0.02% by weight to 0.1% by weight based on the total reaction and total weight, wherein the stabilizer may be used in a mixture of one or more of phosphorous acid, trimethyl phosphate and triphenyl phosphate.

[0036] Furthermore, it is advantageous to maintain the temperature range of 180°C to 210°C for carrying out the first esterification and transesterification reactions, while the temperature range of 230°C to 240°C is suitable for carrying out the second esterification and transesterification reactions.

[0037] Furthermore, as another preferred specific example, it is preferred that the molar ratio of the acid component to the diol to be added in the first esterification reaction and the second esterification reaction is 1:1.15 to 1:1.5.

[0038] Furthermore, as another preferred specific example, it is preferable to carry out the polycondensation reaction for 70 to 110 minutes at a temperature range of 230°C to 240°C and a vacuum of 0.01 Torr to 2.0 Torr.

[0039] Beneficial effects

[0040] According to the present invention, the following superior effects are achieved: by providing a biodegradable polyester resin prepared by adding a reaction rate control agent and a molecular weight increaser derived from biomass, the disadvantages of existing biodegradable resins, such as reaction time, flexibility, and tensile strength, are overcome, and the natural environment is protected by complete decomposition upon disposal in the natural environment. Specifically, to obtain a biodegradable polyester resin with a reaction rate, flexibility, and tensile strength superior to polybutene-co-adipate terephthalate (a conventional biodegradable polyester resin), a number-average molecular weight of 50 prepared by esterification reaction between glycerol and succinic acid is used. Polyglycerol succinate with a number average molecular weight of 0 to 1,000 is added as a reaction rate control agent derived from biomass to increase the reaction rate in the synthesis of biodegradable polyester resins. Polyglycerol furanoate with a number average molecular weight of 1,000 to 5,000, prepared by esterification of glycerol with 2,5-furandicarboxylic acid, is added as a molecular weight increaser derived from biomass to increase tensile strength. This results in the preparation of polymers with a number average molecular weight of 70,000 or more, a weight average molecular weight of 150,000 or more, an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, and a tensile strength of 400 kgf / cm². 2 The above are biodegradable polyester resins.

[0041] Embodiments of the present invention

[0042] A biodegradable polyester resin prepared by adding a reaction rate controller and a molecular weight increaser derived from biomass is a biodegradable polyester resin that exhibits excellent reaction rate, tensile strength, and durability, and has an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, a number-average molecular weight of over 70,000, a weight-average molecular weight of over 150,000, and a molecular weight of over 400 kgf / cm³. 2 The above tensile strength.

[0043] In this invention, as an aromatic dicarboxylic acid, an aromatic dicarboxylic acid (or its anhydride) containing an aromatic compound in its molecular structure can be used, such as terephthalic acid, dimethyl terephthalate and dimethyl isophthalate, but dimethyl terephthalate is preferred.

[0044] In addition, 1,4-butanediol can be used as the diol component in the biodegradable polyester resin of the present invention.

[0045] In addition, aliphatic (including cyclic aliphatic) dicarboxylic acids (or anhydrides) include succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid and their anhydrides, but these aliphatic (including cyclic aliphatic) dicarboxylic acids or their anhydrides may be used alone or as a mixture of two or more of them.

[0046] In particular, in the method for preparing the aliphatic / aromatic copolyester polymer of the present invention, the weight ratio of aromatic dicarboxylic acid to aliphatic dicarboxylic acid in the acid component is preferably 40:60 to 60:40. In this case, in order to have biodegradability, if the aromatic content of the total acid component exceeds 55% by weight, it will not be biodegradable, so this needs to be noted.

[0047] Meanwhile, as a biomass-derived reaction rate control agent of the present invention, polyglycerol succinate with a number average molecular weight of 500 to 1,000 is synthesized as follows: by adding a catalyst and a stabilizer, an esterification reaction is carried out between biomass-derived glycerol and succinic acid at 150°C to 180°C, water is completely released, the temperature is gradually increased to 230°C, and then a polycondensation reaction is carried out for 5 minutes under a high vacuum of 0.5 Torr to 1 Torr according to reaction formula 1.

[0048] [Reaction Formula 1]

[0049] .

[0050] At this point, the polymerization time is preferably 4 to 10 minutes. When the polymerization time is less than 4 minutes, there may be excess diol residue, and when the polymerization time is more than 10 minutes, there is a risk of gelation.

[0051] Furthermore, in order to increase the tensile strength of the biodegradable polyester resin of the present invention, as a biomass-derived molecular weight increaser in the process of synthesizing the biodegradable polyester resin of the present invention, a polyglycerol furan ester with a number average molecular weight of 2,000 to 5,000 is synthesized by means of the following method as shown in reaction formula 2: by adding a catalyst and a stabilizer, an esterification reaction is carried out between biomass-derived glycerol and 2,5-furandicarboxylic acid at 150°C to 180°C, water is completely released, the temperature is gradually raised to 200°C, and then a polycondensation reaction is carried out at 0.5 Torr to less than 1 Torr for 10 minutes.

[0052] [Reaction 2]

[0053] .

[0054] At this point, when the esterification reaction temperature is below 150°C, water is difficult to release, while when the esterification reaction temperature is above 180°C, deterioration may occur. Furthermore, the polycondensation reaction time is preferably between 8 and 20 minutes. When the polycondensation reaction time is less than 8 minutes, a complete reaction may not be possible, while when the polycondensation reaction time is more than 20 minutes, there is a concern about gelation.

[0055] On the other hand, in the aliphatic / aromatic copolyester biodegradable resin of the present invention, as a one-step synthesis method, an aromatic dicarboxylic acid component, a diol, a catalyst, and a stabilizer are first added, and the temperature is gradually raised to 180°C to 210°C. The theoretical amount of methanol is completely released through transesterification, and then the reaction is terminated. Next, an aliphatic dicarboxylic acid, a reaction rate control agent, and a molecular weight increaser are added, and the temperature is again gradually raised to 230°C to 240°C. Water is completely released through esterification, and then the reaction is terminated. In this case, the weight ratio of aromatic dicarboxylic acid to aliphatic dicarboxylic acid in the total acid component is preferably 40:60 to 60:40.

[0056] In addition, as another one-step synthesis method, an aliphatic dicarboxylic acid, a diol, a catalyst, and a stabilizer are first added, and the temperature is gradually raised to 180°C to 210°C. The theoretical amount of water is completely released through esterification, and then the reaction is terminated. Next, an aromatic dicarboxylic acid, a reaction rate control agent, and a molecular weight increaser are added, and the temperature is again gradually raised to 230°C to 240°C. Methanol is completely released through transesterification, and then the reaction is terminated. At this point, the weight ratio of aromatic dicarboxylic acid to aliphatic dicarboxylic acid in the total acid component is preferably 40:60 to 60:40.

[0057] When the amount of aromatic dicarboxylic acid in the acid component exceeds 60% by weight, the biodegradability decreases significantly, thus making it impossible to obtain the biodegradable resin to be obtained in this invention. Furthermore, when the amount of aromatic dicarboxylic acid in the acid component is less than 40% by weight, the heat resistance may also deteriorate.

[0058] In this invention, when preparing aliphatic / aromatic copolyester resin, dicarboxylic acid and diol are preferably added in a molar ratio of 1:1.15 to 1:1.5.

[0059] At this point, when the amount of diol is less than 1.15 mol, there is a potential decrease in reaction rate and a possible deterioration in color. Furthermore, when the amount of diol is greater than 1.5 mol, manufacturing costs increase, thereby reducing price competitiveness.

[0060] In addition, in the first step of synthesis, esterification or transesterification is carried out by gradually increasing the temperature to 180°C to 210°C.

[0061] At this point, when the reaction temperature is below 180°C, releasing the theoretical amount of water requires a significant amount of time. Furthermore, when the reaction temperature is above 210°C, thermal decomposition may occur, leading to a decrease in physical properties.

[0062] In this way, after terminating the esterification or transesterification reaction, the reaction temperature is gradually increased to initiate the polycondensation reaction, which is the second reaction. When the reaction temperature is below 230°C, the reaction rate slows down, while when the polycondensation temperature is above 240°C, there is a risk of thermal decomposition.

[0063] Meanwhile, in this invention, a catalyst and a stabilizer are added at the beginning of the esterification reaction, transesterification reaction, or polycondensation reaction in the first and second steps.

[0064] At this point, the amount of catalyst added is 0.01% to 0.8% by weight based on the total weight of the composition. If less than 0.01% by weight of catalyst is used, the esterification and transesterification reactions may not proceed smoothly, resulting in longer reaction times and potential color degradation during polycondensation.

[0065] Furthermore, when the amount of catalyst exceeds 0.8% by weight, the reaction rate is faster, but the color deepens and the molecular weight distribution increases, which may cause a deterioration in physical properties.

[0066] Furthermore, it is preferred that the amount of stabilizer added is 0.02% to 0.1% by weight. When the amount of stabilizer added is less than 0.02% by weight, factors that may cause significant deterioration of the color may occur, while when the amount of stabilizer added is greater than 0.1% by weight, the reaction rate is significantly reduced.

[0067] On the other hand, when the biomass-derived reaction rate controller (polyglycerol succinate) is added in amounts less than 0.05% by weight, the yield may decrease and there is a limit to the reduction of the polycondensation reaction time. However, when the reaction rate controller is added in amounts greater than 0.5% by weight, the reaction rate is fast, but there is a high risk of gelation.

[0068] When a biomass-derived molecular weight enhancer (polyglycerol furanoate) is added in an amount less than 0.03% by weight of the total components, the increase in molecular weight during the reaction time is limited. However, when the molecular weight enhancer is added in an amount exceeding 0.1% by weight, the molecular weight distribution may increase and the tensile strength may decrease.

[0069] When disposable products are manufactured from biodegradable polyester resins prepared in this way, which have excellent reaction time (productivity), flexibility and tensile strength, it is possible to produce products with high transparency and high tensile strength.

[0070] In the following text, in order to help to understand the present invention in more detail, while the following Examples 1 to 4 are implemented as embodiments of the present invention, Examples 5 to 7 are compared with Comparative Examples 1 to 3, and the same comparative tests are performed as with Example 8, and the results are shown in Table 1.

[0071] [Example 1]

[0072] In a 500 ml round-bottom flask, 0.45 mol of adipic acid and 1.3 mol of 1,4-butanediol were added. While gradually heating, when the internal temperature reached 80 °C, 0.3 g of polyglycerol succinate as a rate control agent and 0.036 g of tetrabutyl titanate as a catalyst were added. Esterification was carried out while gradually heating to 210 °C to completely release water. Then, 0.55 mol of dimethyl terephthalate, 0.3 g of polyglycerol furfural as a molecular weight increaser, and 0.06 g of tetrabutyl titanate as a catalyst were added. Transesterification was carried out while heating again to 200 °C to completely release ethanol. Finally, 0.05 g of antimony trioxide as a catalyst and 0.02 g of trimethyl phosphate as a stabilizer were added. Polycondensation was carried out while gradually heating again to 230 °C.

[0073] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 94 minutes, the acid value was 0.73 mg-KOH / g, the number-average molecular weight was 782,000, and the tensile strength was 472 kgf / cm². 2 The weight-average molecular weight is 153,000.

[0074] [Example 2]

[0075] In a 500 ml round-bottom flask, 0.5 mol of dimethyl terephthalate, 1.35 mol of 1,4-butanediol, and 0.5 g of polyglycerol succinate were added. While gradually heating, 0.037 g of tetrabutyl titanate as a catalyst was added when the internal temperature reached 80 °C. The transesterification reaction was carried out while gradually heating to 210 °C to completely release methanol. Then, 0.5 mol of adipic acid and 0.04 g of tetrabutyl titanate as a catalyst were added, and the esterification reaction was carried out while heating again to 210 °C to completely release water. Finally, 0.6 g of polyglycerol furanoate as a molecular weight increaser, 0.07 g of antimony trioxide as a catalyst, and 0.021 g of trimethyl phosphate as a stabilizer were added, and polycondensation was carried out while gradually heating to 235 °C.

[0076] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 84 minutes, the acid value was 0.61 mg-KOH / g, the number-average molecular weight was 82,000, and the tensile strength was 510 kgf / cm. 2 The weight-average molecular weight is 171,000.

[0077] [Example 3]

[0078] In a 500 ml round-bottom flask, 0.42 mol of adipic acid and 1.4 mol of 1,4-butanediol were added. Then, while gradually heating, 0.7 g of polyglycerol succinate and 0.041 g of tetrabutyl titanate as a catalyst were added when the internal temperature reached 80 °C. Esterification was carried out while gradually heating to 210 °C to completely release methanol. Next, 0.58 mol of dimethyl terephthalate, 0.6 g of polyglycerol furfural, and 0.04 g of tetrabutyl titanate as a catalyst were added. Transesterification was carried out while heating again to 210 °C to completely release water. Finally, 0.05 g of zinc oxide as a catalyst and 0.017 g of trimethyl phosphate as a stabilizer were added. Polycondensation was carried out while gradually heating to 235 °C.

[0079] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 74 minutes, the acid value was 0.51 mg-KOH / g, the number-average molecular weight was 81,000, and the tensile strength was 515 kgf / cm². 2 The weight-average molecular weight is 171,000.

[0080] [Example 4]

[0081] In a 500 ml round-bottom flask, 0.49 mol of adipic acid, 1.45 mol of 1,4-butanediol, and 0.45 g of polyglycerol succinate were added. While gradually heating, 0.032 g of tetrabutyl titanate as a catalyst was added when the internal temperature reached 80 °C. Esterification was carried out while gradually heating to 210 °C to completely release methanol. Then, 0.51 mol of dimethyl terephthalate, 0.7 g of polyglycerol furfural as a molecular weight increaser, and 0.033 g of tetrabutyl titanate as a catalyst were added. The reaction was carried out again while heating to 210 °C to completely release water. Finally, 0.032 g of antimony trioxide as a catalyst and 0.014 g of trimethyl phosphate as a stabilizer were added. Polycondensation was carried out while gradually heating to 235 °C.

[0082] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 93 minutes, the acid value was 0.79 mg-KOH / g, the number-average molecular weight was 78,000, and the tensile strength was 500 kgf / cm. 2 The weight-average molecular weight is 169,000.

[0083] [Example 5]

[0084] As Comparative Example 1, 0.45 mol of dimethyl terephthalate and 1.4 mol of 1,4-butanediol were added to a 500 ml round-bottom flask. Then, while gradually heating, 0.052 g of tetrabutyl titanate as a catalyst was added when the internal temperature reached 80 °C. An esterification reaction was carried out while gradually heating to 210 °C to completely release methanol. Next, 0.55 mol of adipic acid, 0.3 g of malic acid, and 0.038 g of tetrabutyl titanate as a catalyst were added. An esterification reaction was carried out while heating again to 210 °C to completely release water. Then, 0.05 g of antimony trioxide as a catalyst and 0.019 g of trimethyl phosphate as a stabilizer were added. Polycondensation was carried out while gradually heating to 240 °C.

[0085] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 210 minutes, the acid value was 3.4 mg-KOH / g, the number-average molecular weight was 41,000, and the tensile strength was 330 kgf / cm. 2 The weight-average molecular weight is 98,000.

[0086] [Example 6]

[0087] As Comparative Example 2, in a 500 ml round-bottom flask, 0.45 mol of dimethyl terephthalate, 1.3 mol of 1,4-butanediol, and 0.1 mol of ethylene glycol were added. Then, while gradually heating, 0.052 g of tetrabutyl titanate as a catalyst was added when the internal temperature reached 80 °C. An esterification reaction was carried out while gradually heating to 210 °C to completely release methanol. Next, 0.55 mol of adipic acid and 0.038 g of tetrabutyl titanate as a catalyst were added, and an esterification reaction was carried out while heating again to 210 °C to completely release water. Then, 0.05 g of antimony trioxide as a catalyst and 0.019 g of triphenyl phosphate as a stabilizer were added, and polycondensation was carried out while gradually heating to 235 °C.

[0088] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 220 minutes, the acid value was 3.8 mg-KOH / g, the number-average molecular weight was 39,000, and the tensile strength was 290 kgf / cm². 2The weight-average molecular weight is 78,000.

[0089] [Example 7]

[0090] As Comparative Example 3, 0.55 mol of dimethyl terephthalate and 1.4 mol of 1,4-butanediol were added to a 500 ml round-bottom flask. Then, while gradually heating, 0.052 g of tetrabutyl titanate as a catalyst was added when the internal temperature reached 80 °C. The transesterification reaction was carried out while gradually heating to 210 °C to completely release methanol. Next, 0.45 mol of adipic acid and 0.03 g of tetrabutyl titanate as a catalyst were added, and an esterification reaction was carried out while heating again to 210 °C to completely release water. Then, 0.05 g of antimony trioxide as a catalyst and 0.019 g of triphenyl phosphate as a stabilizer were added, and polycondensation was carried out while gradually heating to 240 °C.

[0091] Biodegradable copolyester resins were prepared from the copolyester resin obtained therefrom. The polycondensation reaction time was 270 minutes, the acid value was 3.7 mg-KOH / g, the number-average molecular weight was 38,000, and the tensile strength was 310 kgf / cm. 2 The weight-average molecular weight is 89,000.

[0092] [Example 8]

[0093] [Measuring the physical properties of the resin]

[0094] The physical properties of the resin were measured using the following method, and the results are shown in Table 1.

[0095] [Methods for measuring tensile strength]

[0096] Tensile strength was measured using the ISO 527 test method. A 20-micron film sample was prepared and the measurement was performed at a rate of 500 mm / min.

[0097] [Molecular weight measurement methods]

[0098] The molecular weight was measured using polystyrene as a reference material and a molecular weight measurement device (GPC).

[0099] [Acid Value Measurement Method]

[0100] 1. Collect samples (weigh).

[0101] 2. Dissolve the sample in chloroform or dichloromethane.

[0102] 3. When the sample is completely dissolved, add 2 to 3 drops of phenolphthalein.

[0103] (Indicator preparation method - ethanol (90%) + phenolphthalein (10%))

[0104] 4.0.1 N-KOH-ethanol titrant

[0105] The molecular weight of KOH → 56.11, 0.1 N → 5.611g

[0106] Add 6.60 g (5.611 / 0.85) KOH to a 1 L flask. First, dissolve about 20 ml of KOH in H2O, then dissolve the KOH in ethanol until the water level reaches the 1 L mark.

[0107] 5. Add the titrant from step 4 above to the mixture from step 3 above, measure the amount consumed, and continue until the color turns red for about 30 seconds.

[0108] [Table 1]

[0109]

[0110] The above description merely illustrates the technical essence of the present invention. Various changes and modifications can be made by those skilled in the art without departing from the fundamental characteristics of the invention. Therefore, the exemplary embodiments disclosed in this disclosure are not intended to limit the technical essence of the disclosure, but rather to describe the disclosure. The scope of the technical essence of the disclosure is not limited by these exemplary embodiments. The scope of protection of the present invention should be interpreted based on the appended claims, and all technical essences within their equivalent scope should be understood to fall within the scope of the present invention.

Claims

1. A biodegradable polyester resin prepared by esterification and polycondensation, comprising: adding an acid component comprising dimethyl terephthalate and adipic acid in a weight ratio of 40:60 to 60:40; adding 1,4-butanediol; adding polyglycerol succinate as a reaction rate controller; and adding polyglycerol furanoate as a molecular weight increaser, so that the biodegradable polyester resin has a number average molecular weight of 70,000 or more, a weight average molecular weight of 150,000 or more, an acid value of 0.4 mg-KOH / g to 0.8 mg-KOH / g, and an acid value of 400 kgf / cm³. 2 The above tensile strength, The polyglycerol succinate, which serves as the reaction rate control agent, is prepared according to the following reaction formula 1, via an esterification reaction between glycerol and succinic acid, followed by a polycondensation reaction, to achieve a number average molecular weight of 500 to 1,000. [Reaction Formula 1] ， The polyglycerol furanoate, which serves as the molecular weight increaser, is prepared according to the following reaction formula 2, by an esterification reaction between glycerol and 2,5-furandicarboxylic acid, followed by a polycondensation reaction, to achieve a number average molecular weight of 2,000 to 5,000. [Reaction 2] 。 2. The biodegradable polyester resin according to claim 1, wherein the molar ratio of the acid component to 1,4-butanediol is 1:1.15 to 1:1.

5.

3. The biodegradable polyester resin according to claim 1, wherein at the beginning or end of the esterification reaction and the polycondensation reaction, a catalyst is added in the range of 0.01% to 0.8% by weight based on the total weight of the reactants.

4. The biodegradable polyester resin according to claim 3, wherein the catalyst is a mixture of one or more selected from the group consisting of tetrabutyl titanate, trioctyl antimony oxide, tin oxide, calcium acetate, zinc acetate and tetrapropyl titanate.

5. The biodegradable polyester resin according to claim 1, wherein at the beginning or end of the esterification reaction and the polycondensation reaction, a stabilizer is added in the range of 0.02% to 0.1% by weight based on the total weight of the reactants.

6. The biodegradable polyester resin according to claim 5, wherein the stabilizer is a mixture of one or more selected from phosphorous acid, trimethyl phosphate and triphenyl phosphate.

7. The biodegradable polyester resin according to claim 1, wherein the esterification reaction is carried out by a first esterification reaction at 180°C to 210°C, followed by a second esterification reaction at 230°C to 240°C, and the polycondensation reaction is carried out for 70 to 110 minutes under a vacuum of 0.01 Torr to 2.0 Torr at a temperature range of 230°C to 240°C.

8. The biodegradable polyester resin according to claim 1, wherein the succinic acid is derived from biomass.

9. The biodegradable polyester resin according to claim 1, wherein the 2,5-furandicarboxylic acid is derived from biomass.

10. The biodegradable polyester resin of claim 1, wherein the polyglycerol succinate is added in the range of 0.05% to 0.5% by weight based on the total weight of the reactants.

11. The biodegradable polyester resin of claim 1, wherein the polyglycerol furanoate is added in the range of 0.03% to 0.1% by weight based on the total weight of the reactants.

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