Biodegradable polyester resin having excellent mechanical properties and preparation method therefor

Abstract

The present invention relates to a biodegradable polyester resin and a preparation method therefor, and more specifically to a polyester resin and a preparation method therefor, the polyester resin comprising, in a specific molar ratio, a repeating unit derived from a diol component comprising a nitrogen-containing diol compound and an anhydrosugar alcohol-alkylene oxide adduct, and a repeating unit derived from a dicarboxylic component, and the polyester resin exhibiting excellent mechanical properties and biodegradability simultaneously.

Description

Biodegradable polyester resin with excellent mechanical properties and method for producing the same

[0001] The present invention relates to a biodegradable polyester resin and a method for producing the same, and more particularly, to a polyester resin comprising a repeating unit derived from a diol component including a nitrogen-containing diol compound and an anhydrosugar alcohol-alkylene oxide adduct at a specific molar ratio and a repeating unit derived from a dicarboxylic component, and exhibiting both excellent mechanical properties and biodegradability, and a method for producing the same.

[0002] Hydrogenated sugars (also called “sugar alcohols”) are compounds obtained by adding hydrogen to the reducing end groups of sugars, generally HOCH2(CHOH). n It has the chemical formula CH2OH (where n is an integer from 2 to 5) and is classified into tetrintol, pentitol, hexitol, and heptitol (having 4, 5, 6, and 7 carbon atoms, respectively) depending on the number of carbon atoms. Among them, hexitols with 6 carbon atoms include sorbitol, mannitol, iditol, galactitol, etc., and sorbitol and mannitol are particularly useful substances.

[0003] Anhydrosugar alcohol is a substance formed by removing one or more water molecules from the interior of hydrogenated sugar. When one water molecule is removed, it has the form of a tetraol with four hydroxyl groups in the molecule. When two water molecules are removed, it has the form of a diol with two hydroxyl groups in the molecule. It can be manufactured using hexitol derived from starch (e.g., Korean Patent Registration No. 10-1079518, Korean Patent Publication No. 10-2012-0066904). Anhydrosugar alcohol has been the subject of much interest for a long time and research on its manufacturing method has been conducted because it is an environmentally friendly substance derived from renewable natural resources. Among these anhydrosugar alcohols, isosorbide manufactured from sorbitol currently has the widest range of industrial applications.

[0004] Anhydrous alcohols have a wide range of applications, including treating heart and vascular diseases, as adhesives for patches, as pharmaceuticals such as mouthwashes, as solvents in cosmetics compositions, and as emulsifiers in the food industry. Furthermore, they can raise the glass transition temperature of polymers such as polyester, PET, polycarbonate, polyurethane, and epoxy resin, improving their strength. As an eco-friendly material derived from natural resources, they are also very useful in the plastics industry, including bioplastics. Furthermore, they are known to be useful as eco-friendly solvents for adhesives, eco-friendly plasticizers, biodegradable polymers, and water-soluble lacquers.

[0005] As such, anhydrous alcohols are receiving much attention due to their diverse potential uses, and their use in actual industries is gradually increasing.

[0006] Meanwhile, efforts are being made to reduce fossil fuel consumption to address issues such as the depletion of fossil resources, the increase in atmospheric carbon dioxide due to mass consumption of petroleum resources, and the resulting global warming. In this regard, interest in environmentally friendly polymers is growing, and research is actively underway on polyester resins using biomass raw materials such as anhydrous sugar alcohols.

[0007] Aliphatic polyester resins derived from biomass are widely used in packaging materials, molded products, and films. They are an eco-friendly plastic that is free of endocrine disruptors. Furthermore, their biodegradability has attracted attention as an environmentally friendly material that can address the growing issue of environmental pollution caused by waste plastic.

[0008] Recently, as the harmful effects of bisphenol A have been revealed in polycarbonate, which is mainly used in heat-resistant food containers, the need for environmentally friendly, transparent, and heat-resistant polyester resins is increasing.

[0009] Conventional homopolyesters composed of terephthalic acid and ethylene glycol can improve mechanical properties and heat resistance to some extent through stretch crystallization and heat setting, but their applications and improvements in heat resistance are limited. Therefore, a method has recently been developed to improve the heat resistance of polyester resins by using isosorbide, a biomass-derived compound derived from starch, as a comonomer. However, isosorbide is a secondary alcohol, so its low reactivity makes it difficult to form high-viscosity polyester resins used in the production of sheets and bottles.

[0010] Furthermore, polybutylene adipate-co-terephthalate (PBAT), a representative biodegradable aliphatic polyester resin, is a copolymer containing aliphatic and aromatic compounds and possesses diverse processability. However, its high unit price significantly increases the cost of products such as packaging films manufactured using it as a raw material. Furthermore, it suffers from poor mechanical properties.

[0011] Therefore, there is a need for the development of a polyester resin that is environmentally friendly and exhibits excellent biodegradability while improving the problem of poor mechanical properties of conventional biodegradable polyester resins (e.g., PBAT resin).

[0012] The present invention is intended to solve the problems of the above-mentioned prior art, and the purpose of the present invention is to provide a polyester resin that is environmentally friendly and exhibits excellent mechanical properties and biodegradability, and a method for producing the same.

[0013] In order to achieve the above technical task, the present invention provides a biodegradable polyester resin comprising a repeating unit derived from a dicarboxylic component and a repeating unit derived from a diol component, wherein the diol component comprises a nitrogen-containing diol compound and an anhydrosugar alcohol-alkylene oxide adduct, and the nitrogen-containing diol compound content within 100 mol% of the total diol component is more than 25 mol% and less than 75 mol%.

[0014] According to another aspect of the present invention, a method for producing a biodegradable polyester resin is provided, comprising the steps of (1) subjecting a dicarboxylic component and a diol component to an esterification reaction or an ester exchange reaction; and (2) subjecting the reaction product obtained in step (1) to a polycondensation reaction, wherein the diol component includes a nitrogen-containing diol compound and an anhydrous sugar alcohol-alkylene oxide adduct, and the nitrogen-containing diol compound content within 100 mol% of the total diol component is more than 25 mol% and less than 75 mol%.

[0015] According to another aspect of the present invention, a molded article comprising a biodegradable polyester resin according to the present invention is provided.

[0016] The biodegradable polyester resin according to the present invention is environmentally friendly because it can be manufactured using anhydrous sugar alcohol derived from renewable natural resources, and has superior mechanical properties compared to conventional biodegradable polyester resins, and at the same time exhibits superior biodegradability, so it can be particularly suitably applied to material fields that require both biodegradability and mechanical properties.

[0017] Hereinafter, the present invention will be described in more detail.

[0018] The biodegradable polyester resin of the present invention comprises a repeating unit derived from a dicarboxylic component; and a repeating unit derived from a diol component.

[0019] In one embodiment, the dicarboxylic component comprises an aliphatic dicarboxylic compound, an alicyclic dicarboxylic compound, an aromatic dicarboxylic compound, or a combination thereof.

[0020] More specifically, the aliphatic dicarboxylic compound may include at least one selected from the group consisting of succinic acid or an ester thereof, glutaric acid or an ester thereof, adipic acid or an ester thereof, sebacic acid or an ester thereof, isodecylsuccinic acid or an ester thereof, maleic acid or an ester thereof, fumaric acid or an ester thereof, azelaic acid or an ester thereof, itaconic acid or an ester thereof, glutamic acid or an ester thereof, undecanedioic acid or an ester thereof, dodecanedioic acid or an ester thereof, tridecanedioic acid or an ester thereof, tetradecanedioic acid or an ester thereof, and combinations thereof; The above-mentioned cyclic dicarboxylic compound may include at least one selected from the group consisting of cyclohexanedicarboxylic acid or an ester thereof, 2,5-furandicarboxylic acid or an ester thereof, tetrahydrofuran-2,5-dicarboxylic acid or an ester thereof, tetrahydrofuran-3,5-dicarboxylic acid or an ester thereof, and combinations thereof; and the above-mentioned aromatic dicarboxylic compound may include at least one selected from the group consisting of terephthalic acid or an ester thereof, isophthalic acid or an ester thereof, and combinations thereof, but is not limited thereto.

[0021] More specifically, the dicarboxylic component may include at least one selected from the group consisting of glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, esters thereof, and combinations thereof.

[0022] In one specific embodiment, the ester of the dicarboxylic acid may be a monoester, a diester or a mixture thereof of the dicarboxylic acid, and preferably a diester.

[0023] In one specific example, the ester of the dicarboxylic acid may be, but is not limited to, an alkyl ester of the dicarboxylic acid (more specifically, a mono- or di-(C1-C4)alkyl ester, such as a dimethyl ester or a diethyl ester, etc.).

[0024] In the present invention, the diol component includes a nitrogen-containing diol compound and an anhydrous sugar alcohol-alkylene oxide adduct.

[0025] In one specific example, the nitrogen-containing diol compound may be a reaction product of a nitrogen-containing monomer having a hydroxy group and urea.

[0026] In one specific example, the nitrogen-containing monomer having a hydroxy group may include an amine alcohol.

[0027] More specifically, the nitrogen-containing diol compound may be a compound represented by the following chemical formula 1 or a mixture of two or more thereof.

[0028] [Chemical Formula 1]

[0029]

[0030] In the above chemical formula 1,

[0031] n is an integer from 2 to 6, independently.

[0032] In the present invention, the content of the nitrogen-containing diol compound within 100 mol% of the total diol component is greater than 25 mol% and less than 75 mol%. If the content of the nitrogen-containing diol compound within 100 mol% of the total diol component is 25 mol% or less, the mechanical properties (e.g., tensile strength) and biodegradability of the polyester resin deteriorate, and conversely, if the content is 75 mol% or more, the mechanical properties (e.g., tensile strength) of the polyester resin deteriorate.

[0033] In one specific example, the content of the nitrogen-containing diol compound within 100 mol% of the total diol component may be, for example, greater than 25 mol%, 26 mol% or more, 28 mol% or more, 30 mol% or more, 32 mol% or more, 35 mol% or more, 37 mol% or more, or 40 mol% or more, and may also be, but is not limited to, less than 75 mol%, 74 mol% or less, 72 mol% or less, 70 mol% or less, 68 mol% or less, 65 mol% or less, 63 mol% or less, or 60 mol% or less.

[0034] In the present invention, the anhydrous sugar alcohol-alkylene oxide adduct (also referred to as “anhydrous sugar alcohol-alkylene glycol”) included in the diol component is an adduct obtained by reacting hydroxyl groups at both terminals or one terminal (preferably both terminals) of anhydrous sugar alcohol with an alkylene oxide, and means a compound in which hydrogen at both terminals or one terminal (preferably both terminals) of anhydrous sugar alcohol is replaced with a hydroxyalkyl group, which is a ring-opened form of an alkylene oxide.

[0035] In one embodiment, the alkylene oxide may be a linear alkylene oxide having 2 to 8 carbon atoms or a branched alkylene oxide having 3 to 8 carbon atoms, and more specifically, may be ethylene oxide, propylene oxide, or a combination thereof.

[0036] The above anhydrous sugar alcohol can be produced by dehydration of hydrogenated sugars derived from natural products. Hydrogenated sugar (also called “sugar alcohol”) refers to a compound obtained by adding hydrogen to the reducing terminal group of a sugar, and is generally expressed as HOCH2(CHOH). nIt has the chemical formula CH2OH (where n is an integer from 2 to 5) and is classified into tetrintol, pentitol, hexitol, and heptitol (having 4, 5, 6, and 7 carbon atoms, respectively) depending on the number of carbon atoms. Among them, hexitols with 6 carbon atoms include sorbitol, mannitol, iditol, galactitol, etc., and sorbitol and mannitol are particularly useful substances.

[0037] The above anhydrous alcohol may be monoanhydrous alcohol, dianhydrous alcohol or a mixture thereof, and although not particularly limited, dianhydrous alcohol may be used.

[0038] Monoanhydrosugar alcohol is an anhydrosugar alcohol formed by removing one water molecule from the interior of a hydrogenated sugar, and has a tetraol form with four hydroxyl groups in the molecule. In the present invention, the type of monoanhydrosugar alcohol is not particularly limited, but preferably, it may be monoanhydrosugar hexitol, and more specifically, it may be 1,4-anhydrohexitol, 3,6-anhydrohexitol, 2,5-anhydrohexitol, 1,5-anhydrohexitol, 2,6-anhydrohexitol, or a mixture of two or more thereof.

[0039] Anhydrosugar alcohols are anhydrosugar alcohols formed by the removal of two water molecules from the interior of hydrogenated sugars. They have a diol structure with two hydroxyl groups within the molecule and can be manufactured using hexitols derived from starch. Anhydrosugar alcohols have long been the subject of considerable interest and research into their manufacturing methods, as they are environmentally friendly substances derived from renewable natural resources. Among these dianhydrosugar alcohols, isosorbide, manufactured from sorbitol, currently has the widest range of industrial applications.

[0040] The type of the above-mentioned dianhydrosugar alcohol is not particularly limited, but preferably it may be a dianhydrosugar hexitol, and more specifically, it may be 1,4:3,6-dianhydrohexitol. The above-mentioned 1,4:3,6-dianhydrohexitol may be isosorbide, isomannide, isoidide, or a mixture of two or more thereof.

[0041] In one specific example, the anhydrous alcohol-alkylene oxide adduct may be a compound represented by the following chemical formula 2 or a mixture of two or more thereof.

[0042] [Chemical Formula 2]

[0043]

[0044] In the above chemical formula 2,

[0045] R 1 and R 2 Each independently represents a linear or branched alkylene group having 2 to 8 carbon atoms,

[0046] m and n each independently represent an integer from 0 to 15,

[0047] m+n represents an integer from 1 to 30.

[0048] More preferably, in the above chemical formula 2,

[0049] R 1 and R 2 Each independently represents an ethylene group, a propylene group or an isopropylene group, preferably R 1 and R 2 are identical to each other,

[0050] m and n each independently represent an integer from 0 to 14,

[0051] However, m+n is an integer greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3, and also an integer less than or equal to 25, less than or equal to 20, less than or equal to 15, or less than or equal to 12, for example, an integer from 1 to 25, preferably an integer from 2 to 20, and more preferably an integer from 3 to 15.

[0052] In one specific example, the anhydrous alcohol-alkylene oxide adduct may be an anhydrous alcohol-propylene oxide adduct represented by the following chemical formula 2-1, an anhydrous alcohol-ethylene oxide adduct represented by the following chemical formula 2-2, or a mixture thereof.

[0053] [Chemical Formula 2-1]

[0054]

[0055] In the above chemical formula 2-1,

[0056] a and b each independently represent an integer from 0 to 15,

[0057] a+b represents an integer from 1 to 30.

[0058] More preferably, in the chemical formula 2-1,

[0059] a and b each independently represent an integer from 0 to 14,

[0060] However, a+b is an integer greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3, and also an integer less than or equal to 25, less than or equal to 20, less than or equal to 15, or less than or equal to 12, for example, an integer from 1 to 25, preferably an integer from 2 to 20, and more preferably an integer from 3 to 15.

[0061] [Chemical Formula 2-2]

[0062]

[0063] In the above chemical formula 2-2,

[0064] c and d each independently represent an integer from 0 to 15,

[0065] c+d represents an integer from 1 to 30.

[0066] More preferably, in the above chemical formula 2-2,

[0067] c and d each independently represent an integer from 0 to 14,

[0068] However, c+d is an integer greater than or equal to 1, greater than or equal to 2, or greater than or equal to 3, and also an integer less than or equal to 25, less than or equal to 20, less than or equal to 15, or less than or equal to 12, for example, an integer from 1 to 25, preferably an integer from 2 to 20, and more preferably an integer from 3 to 15.

[0069] In one specific example, the anhydrous sugar alcohol-alkylene oxide adduct may be produced by a production method comprising the steps of (1) treating an anhydrous sugar alcohol with an acid component; and (2) performing an addition reaction between the anhydrous sugar alcohol treated with the acid component obtained in step (1) and an alkylene oxide.

[0070] More specifically, the anhydrous sugar alcohol-alkylene oxide adduct may be produced by a production method comprising the steps of (1) treating an anhydrous sugar alcohol with an acid component; (2) performing an addition reaction between the anhydrous sugar alcohol treated with the acid component obtained in step (1) and an alkylene oxide; and (3) performing an addition reaction between the product obtained in step (2) and an alkylene oxide in the presence of a base catalyst.

[0071] The acid component is not particularly limited, and may be selected from the group consisting of phosphoric acid, sulfuric acid, acetic acid, formic acid, heteropolyacid, or a mixture thereof. In one specific example, the heteropolyacid may be phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, or silicomolybdic acid. In addition, a commercially available acid component such as Amberlyst 15 (manufactured by Dow Chemical) may be used.

[0072] In one specific example, the acid treatment may be performed at an elevated temperature (e.g., 80°C to 200°C, or 90°C to 180°C) under a nitrogen atmosphere using 0.1 to 10 moles, preferably 0.1 to 8 moles, and more preferably 0.1 to 5 moles of the acid component per mole of the anhydrous sugar alcohol, and then vacuum depressurization may be performed to remove moisture within the reactor, but is not limited thereto.

[0073] The acid component used in the above acid treatment is intended to facilitate ring opening of the alkylene oxide in the addition reaction of the alkylene oxide described below.

[0074] Typically, the addition reaction of an alkylene oxide to an alcohol proceeds in the presence of a base catalyst. However, in the case of anhydrosugar alcohols, due to their structural characteristics, the rate at which the alkylene oxide is added competes with the rate at which the anhydrosugar alcohol's ring structure is opened and decomposed by the base catalyst. Accordingly, not only the anhydrosugar alcohol but also the decomposition product of the anhydrosugar alcohol reacts with the alkylene oxide, and the reaction product between the decomposition product of the anhydrosugar alcohol decomposed by the base catalyst and the alkylene oxide can act as a factor that reduces product quality and storage stability. However, if the anhydrosugar alcohol is first treated with an acid component and then the alkylene oxide is added, not only does the acid component facilitate the ring opening of the alkylene oxide, but also the decomposition product of the anhydrosugar alcohol by the base catalyst is not generated, so the addition reaction of the anhydrosugar alcohol and the alkylene oxide can easily produce an anhydrosugar alcohol-alkylene oxide adduct. Therefore, when acid-treated anhydrous sugar alcohol and alkylene oxide are subjected to an addition reaction, the conventional problems can be solved.

[0075] In one specific example, the addition reaction of the anhydrous sugar alcohol treated with the acid component and the alkylene oxide may be carried out at an elevated temperature (e.g., 100°C to 180°C, or 120°C to 160°C) while slowly adding the alkylene oxide to the anhydrous sugar alcohol treated with the acid component for, for example, 1 to 8 hours or 2 to 4 hours, but is not limited thereto. The reaction molar ratio of the anhydrous sugar alcohol and the alkylene oxide is, for example, 1 mol or more or 2 mol or more of the alkylene oxide per 1 mol of the anhydrous sugar alcohol, and also 30 mol or less, 20 mol or less, 15 mol or less, or 12 mol or less, and may be, for example, 1 mol to 30 mol, preferably 2 to 20 mol, but is not limited thereto.

[0076] In one specific example, the addition reaction of the product obtained by the addition reaction of the alkylene oxide with an additional alkylene oxide may be performed, for example, in a high-pressure reactor capable of pressurization (for example, a pressure of 3 MPa or more), in the presence of a base catalyst (for example, a hydroxide of an alkali metal such as sodium hydroxide or potassium hydroxide, or a hydroxide of an alkaline earth metal such as calcium hydroxide), at an elevated temperature (for example, 100°C to 180°C, or 120°C to 160°C), for, for example, 1 hour to 8 hours or 2 hours to 4 hours, but is not limited thereto. The reaction molar ratio of the anhydrous sugar alcohol and the alkylene oxide is, for example, 1 mol or more, 2 mol or more, or 3 mol or more of the alkylene oxide per 1 mol of the anhydrous sugar alcohol, and also 30 mol or less, 20 mol or less, 15 mol or less, or 12 mol or less, and may be, for example, 1 mol to 30 mol, preferably 2 mol to 20 mol, and more preferably 3 mol to 15 mol, but is not limited thereto. Before adding the base catalyst, the acid component used in the treatment can be removed by filtration.

[0077] The product obtained by the addition reaction of an acid-treated anhydrosugar alcohol and an alkylene oxide (i.e., a compound in which an alkylene oxide is added to an anhydrosugar alcohol) has a very stable structure. Therefore, even in the presence of a base catalyst, the ring structure of the anhydrosugar alcohol does not easily open or decompose at high temperatures. Therefore, it is very advantageous for the additional addition reaction of alkylene oxide. If the acid catalyst continues to be used during the additional addition reaction of alkylene oxide, although the acid catalyst helps promote the ring opening of the alkylene oxide, the reaction rate decreases as the number of moles of alkylene oxide added increases. In other words, the rate of alkylene oxide addition competes with the rate of ring opening of the alkylene oxide itself. At this time, the rate of alkylene oxide addition slows down, and the self-condensation reaction and by-product formation of the ring-opened alkylene oxides can occur, which can cause a deterioration in quality. Therefore, the additional addition reaction of alkylene oxide is carried out in the presence of a base catalyst.

[0078] Afterwards, a step of removing metal ions flowing out from the above-mentioned base catalyst may be additionally performed, and for this purpose, a metal ion adsorbent such as Ambosol MP20 (magnesium silicate component) may be used.

[0079] In one specific example, the content of the anhydrous sugar alcohol-alkylene oxide adduct within 100 mol% of the total diol component may be greater than 25 mol% and less than 75 mol%. If the content of the anhydrous sugar alcohol-alkylene oxide adduct within 100 mol% of the total diol component is excessively lower than the above level, the mechanical properties (e.g., tensile strength) of the polyester resin may deteriorate, and conversely, if the content is excessively higher than the above level, the mechanical properties (e.g., tensile strength) and biodegradability of the polyester resin may deteriorate.

[0080] In one specific example, the content of the anhydrous alcohol-alkylene oxide adduct within 100 mol% of the total diol component may be, for example, greater than 25 mol%, greater than 26 mol%, greater than 28 mol%, greater than 30 mol%, greater than 32 mol%, greater than 35 mol%, greater than 37 mol%, or greater than 40 mol%, and may also be, but is not limited to, less than 75 mol%, less than 74 mol%, less than 72 mol%, less than 70 mol%, less than 68 mol%, less than 65 mol%, less than 63 mol%, or less than 60 mol%.

[0081] In one specific example, the diol component may be composed of the nitrogen-containing diol compound and an anhydrous sugar alcohol-alkylene oxide adduct, or alternatively, may further include a diol compound other than these (additional diol component) within a range capable of achieving the purpose of the present invention.

[0082] In one specific embodiment, the additional diol component is specifically an aliphatic diol having 2 to 15 carbon atoms, more specifically an aliphatic diol having 2 to 10 carbon atoms, for example, ethylene glycol, diethylene glycol, triethylene glycol, propane diol (such as 1,2-propane diol and 1,3-propane diol), butane diol (such as 1,2-butane diol, 1,3-butane diol and 1,4-butane diol), pentane diol (such as 1,2-pentane diol, 1,3-pentane diol, 1,4-pentane diol and 1,5-pentane diol), hexane diol (such as 1,2-hexane diol, 1,3-hexane diol, 1,4-hexane diol, 1,5-hexane diol and 1,6-hexane diol), neopentyl glycol, cyclohexane It may be selected from the group consisting of diols (such as 1,2-cyclohexane diol, 1,3-cyclohexane diol, and 1,4-cyclohexane diol), cyclohexane dimethanol (such as 1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, and 1,4-cyclohexane dimethanol), tetramethylcyclobutane diol, tricyclodecane dimethanol, adamantanediol, 2,2-dimethyl-1,3-propane diol, 2-ethyl-2-t-butyl-1,3-propane diol, 2,2,4-trimethyl-1,6-hexane diol, or combinations thereof, but is not limited thereto.

[0083] In one specific example, when the diol component further includes a diol component, the content thereof may be, for example, 1 mol% or more, 3 mol% or more, or 5 mol% or more, and may also be 30 mol% or less, 20 mol% or less, or 10 mol% or less, based on 100 mol% of the total diol component, but is not limited thereto.

[0084] In one specific example, the intrinsic viscosity (IV) of the biodegradable polyester resin of the present invention may be, for example, 0.8 or more, 0.85 or more, 0.86 or more, 0.9 or more, or 1.0 or more, and may be 1.35 or less, 1.3 or less, 1.25 or less, 1.24 or less, or 1.2 or less, but is not limited thereto. The intrinsic viscosity may be measured at 35°C using an Ubbelohd viscometer after dissolving the biodegradable polyester resin in a mixture of phenol and tetrachloroethane (weight ratio = 50:50) to prepare a 0.5 wt% solution.

[0085] In one specific example, the tensile strength of the biodegradable polyester resin of the present invention may be, for example, 23 MPa or more, 24 MPa or more, or 25 MPa or more, but is not limited thereto. The tensile strength of the biodegradable polyester resin may be measured according to ASTM D638.

[0086] In addition, in one specific example, the biodegradable polyester resin of the present invention can exhibit excellent biodegradability, such that the weight loss rate (%) due to biodegradation is 34% or more, 35% or more, or 40% or more after 4 months of burying in standard soil maintained at a temperature of 30 to 40°C and a humidity of 55 to 60%, but is not limited thereto. The standard soil and burying conditions may follow ASTM D5338-92, and the weight loss rate due to biodegradation may be calculated by the following equation.

[0087]

[0088] According to another aspect of the present invention, a method for producing a biodegradable polyester resin is provided, comprising the steps of (1) subjecting a dicarboxylic component and a diol component to an esterification reaction or an ester exchange reaction; and (2) subjecting the reaction product obtained in step (1) to a polycondensation reaction, wherein the diol component includes a nitrogen-containing diol compound and an anhydrous sugar alcohol-alkylene oxide adduct, and the nitrogen-containing diol compound content within 100 mol% of the total diol component is more than 25 mol% and less than 75 mol%.

[0089] The nitrogen-containing diol compound and the anhydrous sugar alcohol-alkylene oxide adduct included in the dicarboxylic component and diol component used in the manufacturing method of the present invention are as described above.

[0090] Additionally, the above diol component may further include an additional diol component other than an anhydrous sugar alcohol and an anhydrous sugar alcohol-alkylene oxide adduct, and such additional diol component is as described above.

[0091] According to one specific example of the present invention, in the step (1), the reaction molar ratio of the diol component to the dicarboxylic component (total moles of the diol component / total moles of the dicarboxylic component) is 1.0 to 2.0, more specifically 1.0 to 1.5, and then the esterification reaction or ester exchange reaction may be performed at a temperature of 60 to 120°C, more specifically 80 to 100°C, optionally in the presence of a catalyst, but is not limited thereto.

[0092] Here, if the reaction molar ratio of the diol component to the dicarboxylic component (total moles of the diol component / total moles of the dicarboxylic component) is less than 1, there is a concern that unreacted dicarboxylic component may remain during the polymerization reaction, which may deteriorate the mechanical properties and color of the polyester resin, and if it exceeds 2.0, there is a concern that the polymerization reaction speed may be too slow, which may deteriorate the productivity of the polyester resin.

[0093] The above esterification reaction time or ester exchange reaction time is usually about 0.5 to 10 hours, more specifically about 1 to 5 hours, and may vary depending on the reaction temperature and pressure, and the reaction molar ratio of the diol component to the dicarboxylic component.

[0094] In one specific example, a catalyst may be used in the esterification reaction or ester exchange reaction (step (1) above) to shorten the reaction time. The esterification reaction or ester exchange reaction (step (1) above) may be performed in a batch or continuous manner, and each reaction raw material may be introduced separately.

[0095] In one specific example, the catalyst for the esterification reaction or ester exchange reaction may be an organic base compound, for example, an amine compound such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), but is not limited thereto.

[0096] In addition, in one specific example, the amount of the catalyst for the esterification reaction or ester exchange reaction may be, for example, 0.1 mol% or more, 0.5 mol% or more, or 1 mol% or more, and may also be 10 mol% or less, 5 mol% or less, or 3 mol% or less, relative to 100 mol% of the total of the diol component and the dicarboxylic component, but is not limited thereto.

[0097] In one specific example, in the step (2), before the initiation of the polycondensation reaction, a polycondensation catalyst and a stabilizer, etc. may be added to the reaction product of the esterification reaction or the ester exchange reaction. As the polycondensation catalyst, any polycondensation catalyst commonly used in this field may be used without limitation, and for example, one or a mixture of two or more selected from titanium compounds, germanium compounds, antimony compounds, aluminum compounds, and tin compounds may be used. As the stabilizer added to the polycondensation reaction, a phosphorus compound may generally be used, and for example, phosphoric acid, trimethyl phosphate, triethyl phosphate, or a mixture thereof may be used.

[0098] In one specific example, the polycondensation reaction may be performed at a temperature of 100 to 200°C, more specifically 110 to 150°C, and under reduced pressure conditions (e.g., 10 mmHg or less), for 2 to 20 hours, more specifically 5 to 15 hours, but is not limited thereto. The reduced pressure conditions are intended to remove by-products of the polycondensation reaction.

[0099] The biodegradable polyester resin according to the present invention is environmentally friendly, has superior mechanical properties compared to conventional biodegradable polyester resins, and simultaneously exhibits superior biodegradability, and therefore can be particularly suitably applied to material fields that require both biodegradability and mechanical properties.

[0100] Therefore, according to another aspect of the present invention, a molded article comprising a biodegradable polyester resin according to the present invention is provided.

[0101] Hereinafter, the present invention will be described in more detail through examples and comparative examples. However, the scope of the present invention is not limited by these examples.

[0102] [Example]

[0103] <Manufacturing Example A: Preparation of nitrogen-containing diol compound>

[0104] Manufacturing Example A1: Manufacturing of di(hydroxyethyl)urea adduct

[0105] 100 g of urea and 203 g of aminoethanol were placed in a reactor equipped with a mechanical stirrer, and the inside of the reactor was purged with nitrogen. The inside of the reactor was heated at a temperature of 130 to 160°C, and the reaction was carried out for 20 to 30 hours. At this time, after the start of the reaction, the ammonia gas generated was released from the reactor by a flow of nitrogen. After the temperature inside the reactor was cooled to 30°C, acetone solvent was added to precipitate the reaction product, the precipitated reaction product was filtered, and the filtrate was washed once more with acetone. Thereafter, the washed reaction product was dried in an oven at 80°C, thereby obtaining 212 g of di(hydroxyethyl)urea adduct.

[0106] Manufacturing Example A2: Manufacturing of di(hydroxypentyl)urea adduct

[0107] The same method as in Preparation Example A1 was performed except that 344 g of aminopentanol was used instead of 203 g of aminoethanol, thereby obtaining 331 g of di(hydroxypentyl)urea adduct.

[0108] Manufacturing Example A3: Manufacturing of di(hydroxyhexyl)urea adduct

[0109] The same method as in Preparation Example A1 was followed, except that 390 g of aminohexanol was used instead of 203 g of aminoethanol, to obtain 375 g of di(hydroxyhexyl)urea adduct.

[0110] <Preparation Example B: Preparation of anhydrous sugar alcohol-alkylene oxide adduct>

[0111] Manufacturing Example B1: Preparation of 5 mol isosorbide-ethylene oxide adduct

[0112] Into a pressurizable reactor, 146 g of isosorbide was placed, and 0.15 g of phosphoric acid (85%) was added as an acid component. The inside of the reactor was purged with nitrogen, heated to 100°C, and moisture inside the reactor was removed through vacuum depressurization. Next, 88 g of ethylene oxide was slowly added to the reactor for the first time, and the reaction was carried out at a temperature of 100°C to 140°C for 2 to 3 hours. The reaction temperature was controlled so as not to exceed 140°C. Afterwards, the internal temperature of the reactor was cooled to 50°C, 0.3 g of potassium hydroxide was added to the reactor, the inside of the reactor was purged with nitrogen, heated to 100°C, and moisture inside the reactor was removed through vacuum depressurization. Next, 132 g of ethylene oxide was slowly added for the second time, and the reaction was carried out at 100°C to 140°C for 2 to 3 hours. When the reaction was completed, the internal temperature of the reactor was cooled to 50°C, 4.0 g of Ambosol MP20 was added as an adsorbent, and the mixture was heated again and stirred at a temperature of 100°C to 120°C for 1 to 5 hours to remove metal ions. At this time, the interior of the reactor was purged with nitrogen and / or vacuum pressure was applied. When no more metal ions were detected, the internal temperature of the reactor was cooled to 60°C to 90°C, and the residual byproducts were removed, thereby obtaining 362 g of a transparent liquid isosorbide-ethylene oxide 5-mole adduct.

[0113] Manufacturing Example B2: Preparation of 10 mol isosorbide-ethylene oxide adduct

[0114] Except that the secondary input of ethylene oxide was changed from 132 g to 352 g, the same method as in Manufacturing Example B1 was performed to obtain 551 g of a 10-mol isosorbide-ethylene oxide adduct in a transparent liquid state.

[0115] Manufacturing Example B3: Preparation of 5 mol isosorbide-propylene oxide adduct

[0116] Instead of using ethylene oxide as an additional reaction raw material, propylene oxide was used, and specifically, instead of first adding 88 g of ethylene oxide, 116 g of propylene oxide was first added, and instead of second adding 132 g of ethylene oxide, 174 g of propylene oxide was second added, the same method as in Manufacturing Example B1 was performed, thereby obtaining 423 g of a transparent liquid isosorbide-propylene oxide 5 mol adduct.

[0117] Manufacturing Example B4: Preparation of 10 mol isosorbide-propylene oxide adduct

[0118] Instead of using ethylene oxide as an additional reaction raw material, propylene oxide was used, and specifically, instead of first adding 88 g of ethylene oxide, 116 g of propylene oxide was first added, and instead of second adding 132 g of ethylene oxide, 465 g of propylene oxide was second added, the same method as in Manufacturing Example B1 was performed, thereby obtaining 698 g of a 10-mol isosorbide-propylene oxide adduct in a transparent liquid state.

[0119] <Manufacture of nitrogen-containing biodegradable polyester>

[0120] Example A1: Production of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0121] In a three-necked glass reactor equipped with a stirrer, 125 g (0.54 mol) of the compound of Preparation Example A2, 100 g (0.54 mol) of the compound of Preparation Example B1, and 173 g (1.08 mol) of dimethyl glutarate were placed, and 2 mol% (based on 100 mol% of the total of the diol component and the dicarboxylic component) of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a reaction catalyst was added, and the mixture was heated to 90°C while mixing. After aging and stirring at 90°C for 2 hours, the mixture was heated to 130°C under reduced pressure conditions (gradually reduced from normal pressure to 1 mmHg), and then reacted while stirring for 8 hours. After completion of the reaction, the reaction product was cooled to room temperature, thereby obtaining 336 g of a nitrogen-containing biodegradable polyester of the following chemical formula A.

[0122] [Chemical Formula A]

[0123]

[0124] Example A2: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B2 as diol components and dimethyl glutarate as a dicarboxylic component.

[0125] By performing the same method as Example A1, except that the content of the compound of Preparation Example A2 was changed from 125 g (0.54 mol) to 79 g (0.34 mol), 100 g (0.34 mol) of the compound of Preparation Example B2 was used instead of the compound of Preparation Example B1, and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 109 g (0.68 mol), 279 g of a nitrogen-containing biodegradable polyester of the following chemical formula B was obtained.

[0126] [Chemical Formula B]

[0127]

[0128] Example A3: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B3 as diol components and dimethyl glutarate as a dicarboxylic component.

[0129] By performing the same method as Example A1, except that the content of the compound of Preparation Example A2 was changed from 125 g (0.54 mol) to 110 g (0.47 mol), the compound of Preparation Example B3 was used 100 g (0.47 mol) instead of the compound of Preparation Example B1, and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 152 g (0.94 mol), 320 g of a nitrogen-containing biodegradable polyester of the following chemical formula C was obtained.

[0130] [Chemical Formula C]

[0131]

[0132] Example A4: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B4 as diol components and dimethyl glutarate as a dicarboxylic component.

[0133] By performing the same method as Example A1, except that the content of the compound of Preparation Example A2 was changed from 125 g (0.54 mol) to 66 g (0.29 mol), 100 g (0.29 mol) of the compound of Preparation Example B4 was used instead of the compound of Preparation Example B1, and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 91 g (0.58 mol), 243 g of a nitrogen-containing biodegradable polyester of the following chemical formula D was obtained.

[0134] [Chemical Formula D]

[0135]

[0136] Example A5: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0137] By performing the same method as Example A1, except that the compound content of Manufacturing Example A2 was changed from 125 g (0.54 mol) to 188 g (0.81 mol) and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 216 g (1.35 mol), 428 g of a nitrogen-containing biodegradable polyester of the above chemical formula A was obtained.

[0138] Example A6: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0139] By performing the same method as Example A1, except that the compound content of Manufacturing Example A2 was changed from 125 g (0.54 mol) to 300 g (1.29 mol) and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 293 g (1.83 mol), 613 g of a nitrogen-containing biodegradable polyester of the above chemical formula A was obtained.

[0140] Example A7: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0141] By performing the same method as Example A1, except that the compound content of Manufacturing Example A2 was changed from 125 g (0.54 mol) to 81 g (0.35 mol) and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 142 g (0.89 mol), 276 g of a nitrogen-containing biodegradable polyester of the above chemical formula A was obtained.

[0142] Example A8: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0143] By performing the same method as Example A1, except that the compound content of Manufacturing Example A2 was changed from 125 g (0.54 mol) to 53 g (0.23 mol) and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 122 g (0.77 mol), 231 g of a nitrogen-containing biodegradable polyester of the above chemical formula A was obtained.

[0144] Example A9: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl 1,4-cyclohexanedicarboxylate as a dicarboxylic component.

[0145] By performing the same method as Example A1 except that 216 g (1.08 mol) of dimethyl 1,4-cyclohexanedicarboxylate was used instead of 173 g (1.08 mol) of dimethyl glutarate, 308 g of a nitrogen-containing biodegradable polyester of the following chemical formula E was obtained.

[0146] [Chemical Formula E]

[0147]

[0148] Example A10: Production of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl terephthalate as a dicarboxylic component.

[0149] By performing the same method as Example A1 except that 209 g (1.08 mol) of dimethyl terephthalate was used instead of 173 g (1.08 mol) of dimethyl glutarate, 332 g of a nitrogen-containing biodegradable polyester of the following chemical formula F was obtained.

[0150] [Chemical formula F]

[0151]

[0152] Example A11: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate and dimethyl 1,4-cyclohexanedicarboxylate as dicarboxylic components.

[0153] By performing the same method as Example A1, except that 86 g (0.54 mol) of dimethyl glutarate and 108 g (0.54 mol) of dimethyl 1,4-cyclohexanedicarboxylate were used instead of 173 g (1.08 mol) of dimethyl glutarate, 321 g of a nitrogen-containing biodegradable polyester of the following chemical formula G was obtained.

[0154] [Chemical formula G]

[0155]

[0156] Example A12: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate and dimethyl terephthalate as dicarboxylic components.

[0157] By performing the same method as Example A1, except that 86 g (0.54 mol) of dimethyl glutarate and 105 g (0.54 mol) of dimethyl terephthalate were used instead of 173 g (1.08 mol) of dimethyl glutarate, 316 g of a nitrogen-containing biodegradable polyester of the following chemical formula H was obtained.

[0158] [Chemical formula H]

[0159]

[0160] Example A13: Production of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl 1,4-cyclohexanedicarboxylate and dimethyl terephthalate as dicarboxylic components.

[0161] By performing the same method as Example A1, except that 108 g (0.54 mol) of dimethyl 1,4-cyclohexanedicarboxylate and 105 g (0.54 mol) of dimethyl terephthalate were used instead of 173 g (1.08 mol) of dimethyl glutarate, 362 g of a nitrogen-containing polyester of the following chemical formula I was obtained.

[0162] [Chemical Formula I]

[0163]

[0164] Example A14: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate, dimethyl 1,4-cyclohexanedicarboxylate, and dimethyl terephthalate as dicarboxylic components.

[0165] By performing the same method as Example A1, except that 52 g (0.32 mol) of dimethyl glutarate, 65 g (0.32 mol) of dimethyl 1,4-cyclohexanedicarboxylate and 84 g (0.44 mol) of dimethyl terephthalate were used instead of 173 g (1.08 mol) of dimethyl glutarate, 357 g of a nitrogen-containing polyester of the following chemical formula J was obtained.

[0166] [Chemical formula J]

[0167]

[0168] Example A15: Preparation of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A1 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0169] By performing the same method as Example A1, except that 80 g (0.54 mol) of the compound of Preparation Example A1 was replaced with 125 g (0.54 mol) of the compound of Preparation Example A2, 274 g of a nitrogen-containing biodegradable polyester of the following chemical formula K was obtained.

[0170] [Chemical formula K]

[0171]

[0172] Example A16: Production of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A3 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0173] By performing the same method as Example A1, except that 140 g (0.54 mol) of the compound of Preparation Example A3 was used instead of 125 g (0.54 mol) of the compound of Preparation Example A2, 337 g of a nitrogen-containing biodegradable polyester of the following chemical formula L was obtained.

[0174] [Chemical formula L]

[0175]

[0176] Comparative Example A1: Production of a nitrogen-containing biodegradable polyester using the compound of Preparation Example A1 as a diol component and dimethyl glutarate as a dicarboxylic component.

[0177] By performing the same method as Example A1, except that 160 g (1.08 mol) of the compound of Preparation Example A1 was used alone instead of the compound of Preparation Example A2 and the compound of Preparation Example B1 as the diol component, 216 g of a nitrogen-containing biodegradable polyester was obtained.

[0178] Comparative Example A2: Production of a nitrogen-containing biodegradable polyester using the compound of Preparation Example A2 as a diol component and dimethyl glutarate as a dicarboxylic component.

[0179] Except that 251 g (1.08 mol) of the compound of Preparation Example A2 was used alone instead of the compound of Preparation Example A2 and the compound of Preparation Example B1 as the diol component, the same method as Example A1 was performed to obtain 329 g of a nitrogen-containing biodegradable polyester.

[0180] Comparative Example A3: Production of a nitrogen-containing biodegradable polyester using the compound of Preparation Example A3 as a diol component and dimethyl glutarate as a dicarboxylic component.

[0181] Except that 281 g (1.08 mol) of the compound of Preparation Example A3 was used alone instead of the compounds of Preparation Example A2 and Preparation Example B1 as the diol component, the same method as Example A1 was performed to obtain 343 g of a nitrogen-containing biodegradable polyester.

[0182] Comparative Example A4: Manufacturing of a nitrogen-containing biodegradable polyester using the B1 compound of the manufacturing example as a diol component and dimethyl glutarate as a dicarboxylic component.

[0183] Except that 200 g (1.08 mol) of the compound of Preparation Example B1 was used alone instead of the compound of Preparation Example A2 and the compound of Preparation Example B1 as the diol component, the same method as Example A1 was performed to obtain 223 g of a nitrogen-containing biodegradable polyester.

[0184] Comparative Example A5: Production of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0185] By performing the same method as Example A1, except that the content of the compound of Preparation Example A2 as the diol component was changed from 125 g (0.54 mol) to 375 g (1.61 mol) and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 345 g (2.15 mol), 508 g of a nitrogen-containing biodegradable polyester was obtained.

[0186] Comparative Example A6: Production of a nitrogen-containing biodegradable polyester using the compounds of Preparation Example A2 and Preparation Example B1 as diol components and dimethyl glutarate as a dicarboxylic component.

[0187] By performing the same method as Example A1, except that the content of the compound of Preparation Example A2 as the diol component was changed from 125 g (0.54 mol) to 41 g (0.18 mol) and the content of dimethyl glutarate was changed from 173 g (1.08 mol) to 115 g (0.72 mol), 205 g of a nitrogen-containing biodegradable polyester was obtained.

[0188] Comparative Example A7: Production of a nitrogen-containing biodegradable polyester using the compound of Preparation Example A2 as a diol component and dimethyl glutarate, dimethyl 1,4-cyclohexanedicarboxylate, and dimethyl terephthalate as dicarboxylic components.

[0189] By performing the same method as Example A1, except that only 125 g (0.54 mol) of the compound of Preparation Example A2 was used alone instead of the compound of Preparation Example B1 as the diol component, and 26 g (0.16 mol) of dimethyl glutarate, 32 g (0.16 mol) of dimethyl 1,4-cyclohexanedicarboxylate, and 42 g (0.22 mol) of dimethyl terephthalate were used instead of 173 g (1.08 mol) of dimethyl glutarate as the dicarboxylic component, 126 g of a nitrogen-containing biodegradable polyester was obtained.

[0190] Comparative Example A8: Production of a nitrogen-containing biodegradable polyester using the compound of Preparation Example B1 as a diol component and dimethyl glutarate, dimethyl 1,4-cyclohexanedicarboxylate, and dimethyl terephthalate as dicarboxylic components.

[0191] By performing the same method as Example A1, except that only 100 g (0.54 mol) of the compound of Preparation Example B1 was used alone instead of the compound of Preparation Example A2 as the diol component, and 26 g (0.16 mol) of dimethyl glutarate, 32 g (0.16 mol) of dimethyl 1,4-cyclohexanedicarboxylate, and 42 g (0.22 mol) of dimethyl terephthalate were used instead of 173 g (1.08 mol) of dimethyl glutarate as the dicarboxylic component, 119 g of a nitrogen-containing polyester was obtained.

[0192] The biodegradable polyester resins obtained in the above examples and comparative examples were evaluated for physical properties using the following method, and the results are shown in Table 1 below.

[0193] <Physical property evaluation>

[0194] (1) Intrinsic viscosity (IV): A 0.5 wt% solution was prepared by dissolving a biodegradable polyester resin in a mixture of phenol and tetrachloroethane (weight ratio = 50:50), and the intrinsic viscosity was measured at 35°C using an Ubbelohd viscometer.

[0195] (2) Tensile strength: According to ASTM D638, tensile specimens of the biodegradable polyester resins manufactured in the above examples and comparative examples were prepared, and then the tensile strength was measured using a universal testing machine (UTM). The tensile strength of each specimen was measured a total of five times, and the average value was calculated.

[0196] (3) Soil biodegradability: After freezing and crushing the biodegradable polyester resin chips manufactured in the above examples and comparative examples, the freeze-crushed resin chips were buried in compost maintained at a temperature of 30 to 40°C and a humidity of 55 to 60% to measure biodegradation under compost conditions, and the biodegradability was measured at regular time intervals (after 1 month, after 2 months, and after 4 months). The standard soil and landfill conditions used at this time followed ASTM D5338-92.

[0197]

[0198]

[0199]

[0200]

[0201] As shown in Table 1 above, in the case of the biodegradable polyester resins of Examples A1 to A16 according to the present invention, the intrinsic viscosity of the biodegradable polyester resin was high, the tensile strength was 25 MPa or more, which was excellent in mechanical properties, and the weight reduction rate due to biodegradation was 40% or more after 4 months, which also maintained excellent biodegradability.

[0202] On the other hand, in Comparative Examples A1 to A3 and A7, which used only a nitrogen-containing diol compound as the diol component, the tensile strength was very poor, and in Comparative Examples A4 and A8, which used only an anhydrous sugar alcohol-alkylene oxide adduct as the diol component, a low-molecular-weight polyester resin was obtained due to reduced reactivity, so not only was the tensile strength very poor, but the biodegradability was also very poor. In addition, in Comparative Example A5, the tensile strength was very poor, and in Comparative Example A6, a low-molecular-weight polyester resin was obtained due to reduced reactivity, so the tensile strength was very poor.

Claims

1. A biodegradable polyester resin comprising a repeating unit derived from a dicarboxylic component and a repeating unit derived from a diol component, The above diol component comprises a nitrogen-containing diol compound and an anhydrous sugar alcohol-alkylene oxide adduct, The content of the nitrogen-containing diol compound within the total 100 mol% of the above diol component is more than 25 mol% and less than 75 mol%, Biodegradable polyester resin.

2. A biodegradable polyester resin according to claim 1, wherein the dicarboxylic component comprises an aliphatic dicarboxylic compound, an alicyclic dicarboxylic compound, an aromatic dicarboxylic compound, or a combination thereof.

3. In paragraph 2, The aliphatic dicarboxylic compound comprises at least one selected from the group consisting of succinic acid or an ester thereof, glutaric acid or an ester thereof, adipic acid or an ester thereof, sebacic acid or an ester thereof, isodecylsuccinic acid or an ester thereof, maleic acid or an ester thereof, fumaric acid or an ester thereof, azelaic acid or an ester thereof, itaconic acid or an ester thereof, glutamic acid or an ester thereof, undecanedioic acid or an ester thereof, dodecanedioic acid or an ester thereof, tridecanedioic acid or an ester thereof, tetradecanedioic acid or an ester thereof, and combinations thereof. The alicyclic dicarboxylic compound comprises at least one selected from the group consisting of cyclohexanedicarboxylic acid or an ester thereof, 2,5-furandicarboxylic acid or an ester thereof, tetrahydrofuran-2,5-dicarboxylic acid or an ester thereof, tetrahydrofuran-3,5-dicarboxylic acid or an ester thereof, and combinations thereof. The aromatic dicarboxylic compound comprises at least one selected from the group consisting of terephthalic acid or its ester, isophthalic acid or its ester, and combinations thereof. Biodegradable polyester resin.

4. A biodegradable polyester resin according to claim 1, wherein the nitrogen-containing diol compound is a reaction product of a nitrogen-containing monomer having a hydroxyl group and urea.

5. A biodegradable polyester resin in the first paragraph, wherein the anhydrous sugar alcohol-alkylene oxide adduct is an adduct obtained by reacting hydroxyl groups at both terminals or one terminal of an anhydrous sugar alcohol with an alkylene oxide.

6. A biodegradable polyester resin in paragraph 5, wherein the anhydrous sugar alcohol is an anhydrous sugar hexitol.

7. A biodegradable polyester resin in paragraph 5, wherein the anhydrous sugar alcohol is selected from the group consisting of isosorbide, isomannide, isoidide, or mixtures thereof, and the alkylene oxide is a linear alkylene oxide having 2 to 8 carbon atoms or a branched alkylene oxide having 3 to 8 carbon atoms. 8.(1) A step of esterifying or transesterifying a dicarboxylic component and a diol component; and (2) a step of subjecting the reaction product obtained in step (1) to a polycondensation reaction; The above diol component comprises a nitrogen-containing diol compound and an anhydrous sugar alcohol-alkylene oxide adduct, The content of the nitrogen-containing diol compound within the total 100 mol% of the above diol component is more than 25 mol% and less than 75 mol%, Method for producing biodegradable polyester resin.

9. A method for producing a biodegradable polyester resin in claim 8, wherein the nitrogen-containing diol compound is a reaction product of a nitrogen-containing monomer having a hydroxyl group and urea.

10. A method for producing a biodegradable polyester resin, wherein in step (1), the reaction molar ratio of the diol component to the dicarboxylic component (total moles of the diol component / total moles of the dicarboxylic component) is 1.0 to 2.

0.

11. A molded product comprising a biodegradable polyester resin according to any one of claims 1 to 7.

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