Polyester resin and preparation method thereof

Abstract

Provided is a polyester resin which contains a copolymer containing a repeating unit represented by chemical formula 1, is cross-linked by an ether-based cross-linking agent represented by chemical formula 2, and has a terminal acid value of 5-20 meq / kg. Chemical formula 1 and chemical formula 2 are as described above.

Description

Technical Field

[0001] The invention relates to a polyester resin and a preparation method thereof. Background Art

[0002] Polyester resin refers to a polymer resin having an ester (RO-C(=O)-R') functional group on the main chain, and is used in many industrial fields for packaging, display, insulation materials and other purposes.

[0003] A representative example may be polyethylene terephthalate (PET) resin produced by the reaction of terephthalic acid (TPA) and ethylene glycol (EG).

[0004] However, the main raw material of terephthalic acid is p-xylene produced by purifying crude oil. Therefore, the production and use of terephthalic acid will lead to the depletion of crude oil resources. In addition, when terephthalic acid decomposes, it will increase carbon dioxide emissions, thereby causing environmental pollution and climate change such as the greenhouse effect.

[0005] In this regard, attempts are being made to replace terephthalic acid with 2,5-furandicarboxylic acid (FDCA) when preparing polyester resins. Furandicarboxylic acid, as a biomass-derived material, can prevent the depletion of crude oil resources and minimize environmental pollution, climate change, etc. due to its biodegradability.

[0006] However, furandicarboxylic acid is a compound with low thermal stability, and thermal discoloration such as yellowing and browning occurs during the esterification reaction between furandicarboxylic acid and diol components.

[0007] This problem cannot be solved simply by mixing furandicarboxylic acid with an aliphatic dicarboxylic acid and reacting them with a diol component. Summary of the invention

[0008] Technical issues

[0009] According to one embodiment, a polyester resin is provided, the terminal acid value of which is reduced, thermal discoloration is suppressed, and mechanical properties are improved.

[0010] According to another embodiment, a method for preparing a polyester resin is provided, which can reduce the terminal acid value of the polyester resin to improve physical properties, and inhibit thermal discoloration of the polymer to improve mechanical properties.

[0011] Technical Solution

[0012] The polyester resin of one embodiment includes a copolymer containing a repeating unit represented by Chemical Formula 1, and is cross-linked by an ether cross-linking agent represented by Chemical Formula 2, and has a terminal acid value of 5 meq / kg to 20 meq / kg.

[0013] Chemical formula 1:

[0014]

[0015] Chemical formula 2:

[0016]

[0017] In the chemical formula 1, the A 11 is a straight or branched divalent aliphatic hydrocarbon group having 1 to 15 carbon atoms, wherein R 11 is a halogen group, a hydroxyl group, an alkoxy group or an alkyl group, wherein n 11 is the number of repetitions of the repeating unit, the n 12 is an integer from 0 to 2,

[0018] In the chemical formula 2, the A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

[0019] The Chemical Formula 2 may include Chemical Formula 2A, Chemical Formula 2B, Chemical Formula 2C, Chemical Formula 2D, or a combination thereof.

[0020] Chemical formula 2A:

[0021]

[0022] Chemical formula 2B:

[0023]

[0024] Chemical formula 2C:

[0025]

[0026] Chemical Formula 2D:

[0027]

[0028] The terminal acid value of the polyester resin may be 6 meq / kg to 11 meq / kg.

[0029] The difference between the intrinsic viscosity values ​​of the polyester resin measured at 35° C. and 25° C., ie, ΔIV, may be 0.2 dL / g to 1.6 dL / g.

[0030] According to a CIE 1976 L*a*b* colorimeter, the polyester resin may have an L* value of 94 or more and a b* value of 5.0 or less.

[0031] The polyester resin may have a glass transition temperature (Tg) of 85°C to 100°C, and a melting temperature (Tm) of 200°C to 240°C.

[0032] The elongation of the polyester resin may be 130% or more.

[0033] A method for preparing a polyester resin according to another embodiment includes the following steps: an esterification step of reacting an aromatic dicarboxylic acid compound including a furandicarboxylic acid compound, an aliphatic diol compound, and an ether crosslinking agent represented by Chemical Formula 2 to prepare an oligomer; and

[0034] The step of polymerizing the oligomers is to prepare a polyester resin, wherein the terminal acid value of the polyester resin is 5 meq / kg to 20 meq / kg.

[0035] Chemical formula 2:

[0036]

[0037] In the chemical formula 2, the A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

[0038] The ether cross-linking agent may be added in an amount of 10 ppm to 5000 ppm based on 1 kg of the polyester resin.

[0039] The Chemical Formula 2 may include Chemical Formula 2A, Chemical Formula 2B, Chemical Formula 2C, Chemical Formula 2D, or a combination thereof.

[0040] Chemical formula 2A:

[0041]

[0042] Chemical formula 2B:

[0043]

[0044] Chemical formula 2C:

[0045]

[0046] Chemical Formula 2D:

[0047]

[0048] The aromatic dicarboxylic acid compound may further include isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbene dicarboxylic acid, 2,5-thiophene dicarboxylic acid or a mixture thereof.

[0049] The furan dicarboxylic acid compound may be a compound represented by Chemical Formula 3.

[0050] Chemical formula 3:

[0051]

[0052] In the chemical formula 3, the R 31 is a halogen group, a hydroxyl group, an alkoxy group or an alkyl group, wherein R 32 and R 33 are independently hydroxyl or alkoxy, the n 32 An integer from 0 to 2.

[0053] The aliphatic diol-based compound may be a compound represented by Chemical Formula 4.

[0054] Chemical formula 4:

[0055]

[0056] In the chemical formula 4, the A 11 It is a straight-chain or branched divalent aliphatic hydrocarbon group having 1 to 15 carbon atoms.

[0057] In the esterification reaction step, the molar ratio of the aromatic dicarboxylic acid compound to the aliphatic diol compound may be 1:1.5 to 1:5.0.

[0058] The polymerization step may include the following steps: a prepolymerization step of prepolymerizing the oligomer; and a polycondensation step of polycondensing the polymer formed by the prepolymerization.

[0059] Effects of the Invention

[0060] The polyester resin of one example has a reduced terminal acid value, is suppressed from thermal discoloration, and has improved mechanical properties.

[0061] The method for preparing a polyester resin in another embodiment can reduce the terminal acid value of the polyester resin to improve physical properties, and inhibit thermal discoloration of the polymer to improve mechanical properties. DETAILED DESCRIPTION

[0062] The advantages, features and methods for implementing the technologies described below will become clearer through the accompanying drawings and multiple implementation examples described below. However, the implementation form is not limited to the multiple implementation examples disclosed below. Unless otherwise defined, all terms (including technical terms and scientific terms) used in this specification can use the meanings commonly understood by those skilled in the art. In addition, unless otherwise defined, multiple terms defined in commonly used dictionaries will not be interpreted ideally or excessively.

[0063] Throughout this specification, unless otherwise expressly stated, when a part "includes" a certain constituent element, it does not exclude other constituent elements, but indicates that other constituent elements may be further included. In addition, unless otherwise defined, the singular expression also includes the plural.

[0064] Unless otherwise specified, the term "alkyl" used in this specification refers to a saturated monovalent aliphatic hydrocarbon radical including straight and branched chains having a specific number of carbon atoms. Alkyl groups usually contain 1 to 20 carbon atoms ("C1-C 20 alkyl”), preferably containing 1 to 12 carbon atoms (“C1-C 12 The alkyl group may be substituted or unsubstituted. In particular, unless otherwise specified, the alkyl group may be substituted by one or more halogens, up to the total number of hydrogen atoms on the alkyl residue. Thus, the C1-C4 alkyl group includes halogenated alkyl groups, for example, fluorinated alkyl groups having 1 to 4 carbon atoms, for example, trifluoromethyl (-CF3) or difluoroethyl (-CH2CHF2).

[0065] The arbitrarily substituted alkyl group described in this specification may be substituted with one or more substituents, and unless otherwise specified, the substituents may be independently selected. The total number of substituents may be the same as the total number of hydrogen atoms on the alkyl residue until such substitution satisfies the chemical properties. The arbitrarily substituted alkyl group may generally contain 1 to 6 arbitrary substituents, sometimes contain 1 to 5 arbitrary substituents, preferably contain 1 to 4 arbitrary substituents, and more preferably contain 1 to 3 arbitrary substituents.

[0066] Any substituents suitable for the alkyl group include, but are not limited to, C1-C8 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, C3-C8 cycloalkyl, three-membered to twelve-membered heterocyclic group, C6-C 12Aryl and 5- to 12-membered heteroaryl, halo, =O (oxo), =S (thio), =N-CN, =N-OR x , =NR x 、-CN、-C(O)R x 、-CO2R x 、-C(O)NR x R y 、-SR x 、-SOR x 、-SO2R x 、-SO2NR x R y 、-NO2、-NR x R y 、-NR x C(O)R y 、-NR x C(O)NR x R y 、-NR x C(O)OR x 、-NR x S02R y 、-NR x SO2NR x R y 、-OR x 、-OC(O)R x and -OC(O)NR x R y , each R x and R y can be independently hydrogen (H), C1-C8 alkyl, C1-C8 acyl, C2-C8 alkenyl, C2-C8 alkynyl, C3-C8 cycloalkyl, three-membered to twelve-membered heterocyclic group, C6-C 12 aryl or 5- to 12-membered heteroaryl, or, R x and R y Together with the N atom attached thereto, it may form a three-membered to twelve-membered heterocyclic ring or a five-membered to twelve-membered heteroaromatic ring, each of which may contain any of O, N and S(O) q (in which case q is 0 to 2) 1, 2 or 3 additional heteroatoms, each R x and R yThe alkyl radical may be substituted by 1 to 3 substituents independently selected from halo, =O, =S, =N-CN, =N-OR', =NR', -CN, -C(O)R', -CO2R', -C(O)NR'2, -SOR', -SO2R', -SO2NR'2, -NO2, -NR'2, -NR'C(O)R', -NR'C(O)NR'2, -NR'C(O)OR', -NR'SO2R', -NR'SO2NR'2, -OR', -OC(O)R' and -OC(O)NR'2, in which case each R' may be independently hydrogen (H), C1-C8 alkyl, C1-C8 acyl, C2-C8 alkenyl, C2-C8 alkynyl, C3-C8 cycloalkyl, a three-membered to twelve-membered heterocyclic group, a C6-C 12 Aryl or C5-C 12 heteroaryl, each C1-C8 alkyl, C2-C8 alkenyl, C2-C8 alkynyl, C3-C8 cycloalkyl, three-membered to twelve-membered heterocyclic group, C6-C 12 Aryl and five- to twelve-membered heteroaryl groups are as additionally defined herein and may be optionally substituted.

[0067] Unless otherwise specified, the term "divalent aliphatic hydrocarbon (i.e., alkylene)" used in this specification means a divalent hydrocarbon group that can simultaneously connect two different groups and has a specific number of carbon atoms. Sometimes, alkylene refers to -(CH2) n -(In this case, n is 1 to 8, preferably, n is 1 to 4). In certain cases, the alkylene group may also be substituted by other groups and may contain at least one unsubstituted degree (i.e., an alkenylene residue or an alkynylene residue) or a ring. The open valences of the alkylene group do not have to be at opposite ends of the chain. Therefore, forked alkylene groups, for example, -CH(Me)-, -CH2CH(Me)- and -C(Me)2- are also included in the term "alkylene", as are cyclic groups, for example, cyclopropane-1,1-diyl and unsaturated groups, for example, vinyl (-CH=CH-) or propenyl (-CH2-CH=CH-). The alkylene group may be substituted or unsubstituted by the groups described in the present invention as being applicable to the alkyl group.

[0068] Unless otherwise specified, the term "halo" or "halogen" used in this specification means fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

[0069] Unless otherwise stated, the term "hydroxyl" as used in this specification refers to an -OH group.

[0070] Unless otherwise specified, the term "alkoxy" as used in this specification refers to a monovalent -O-alkyl group having a specific number of carbon atoms in the alkyl portion. Alkoxy groups typically have 1 to 8 carbon atoms ("C1-C8 alkoxy"), or 1 to 6 carbon atoms ("C1-C6 alkoxy"), or 1 to 4 carbon atoms ("C1-C4 alkoxy"). For example, C1-C4 alkoxy groups include methoxy (-OCH3), ethoxy (-OCH2CH3), isopropoxy (-OCH(CH3)2), tert-butoxy (-OC(CH3)3), etc. The alkyl portion of the alkoxy group may be substituted or unsubstituted with the groups described in the present invention as being applicable to the alkyl group. In particular, the alkoxy group may be arbitrarily substituted with one or more halogen atoms, in particular, one or more fluorine atoms, up to the total number of hydrogen atoms on the alkyl portion. Such groups are represented as "haloalkoxy" having a specific number of carbon atoms and substituted with one or more halo groups, for example, when fluorinated, they can be more specifically represented as "fluoroalkoxy". Typically, such groups contain 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and sometimes contain 1 or 2 carbon atoms and 1, 2 or 3 halogen atoms (i.e., "C1-C6 haloalkoxy", "C1-C4 haloalkoxy" or "C1-C2 haloalkoxy"). More specifically, fluorinated alkyl groups can generally be represented as fluoroalkoxy substituted with 1, 2 or 3 fluorine atoms, for example, specifically represented as C1-C6, C1-C4 or C1-C2 fluoroalkoxy. Thus, C1-C4 fluoroalkoxy includes trifluoromethoxy (-OCF3), difluoromethoxy (-OCF2H), fluoromethoxy (-OCFH2), difluoroethoxy (-OCH2CF2H), and the like.

[0071] As used in this specification, the terms "optionally substituted" and "substituted or unsubstituted" are used interchangeably to indicate that the particular group being described has no non-hydrogen substituents at all (i.e., unsubstituted) or that the group may have more than one non-hydrogen substituent (i.e., substituted). Unless otherwise specifically stated, the total number of substituents that may be present is the same as the number of H atoms in the unsubstituted form of the described group. When an optional substituent is attached via a double bond (e.g., oxo (=O)), the total number of other substituents that can occupy the available valences is reduced by 2. When an optional substituent is independently selected from a catalog of alternatives, the selected groups may be the same or different. Throughout the present invention, the number and nature of the optional substituents are limited to the extent that such substitution satisfies the chemical properties.

[0072] In the present specification, * added to both ends of a chemical formula indicates connection to another adjacent chemical formula.

[0073] In this specification, the CIE 1976 L*a*b* colorimetric system is a color space defined by CIE (International Commission on Illumination) as a global standard.

[0074] In this CIE1976 L*a*b* color space, the L* value shows the brightness in the color coordinates, and its range is 0 to 100. When the value is 0, it means completely black, and when it is 100, it means completely white. a* shows which side it leans towards, red or green. When the value is a positive value, i.e., "+", it is red, and when it is a negative value, i.e., "-", it is green. b* shows which side it leans towards, yellow or blue. When the value is a positive value, i.e., "+", it is yellow, and when it is a negative value, i.e., "-", it is blue.

[0075] Based on the above definitions, a number of embodiments of the present invention are described in detail. However, these are examples and the present invention is not limited thereto, but is defined only by the scope of the appended claims.

[0076] Preparation method of polyester resin

[0077] The preparation method of the polyester resin of one embodiment includes the following steps: an esterification reaction step, in which an aromatic dicarboxylic acid compound including a furandicarboxylic acid compound, an aliphatic diol compound, and an ether cross-linking agent represented by Chemical Formula 2 are reacted to prepare an oligomer; and a polymerization step, in which the oligomer is polymerized to prepare a polyester resin, wherein the terminal acid value of the polyester resin is 5 meq / kg to 20 meq / kg.

[0078] Chemical formula 2:

[0079]

[0080] In the chemical formula 2, the A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

[0081] When the method for preparing a polyester resin according to an embodiment is used, the terminal acid value of the polyester resin can be reduced and thermal discoloration can be suppressed by adding an ether crosslinking agent.

[0082] In the esterification reaction step, an aromatic dicarboxylic acid compound including a furandicarboxylic acid compound, an aliphatic diol compound, and an ether-based crosslinking agent represented by Chemical Formula 2 are reacted to prepare an oligomer.

[0083] The furandicarboxylic acid compound may be a biologically derived material.

[0084] The furan dicarboxylic acid-based compound may be a compound represented by Chemical Formula 3.

[0085] Chemical formula 3:

[0086]

[0087] In chemical formula 3, R 31 is a halogen group, a hydroxyl group, an alkoxy group or an alkyl group, R 32 and R 33 are independently hydroxyl or alkoxy, n 32 An integer from 0 to 2.

[0088] For example, the furan dicarboxylic acid compound may be 2,5-furan dicarboxylic acid or its ester. In this case, in Chemical Formula 3, R 32 and R 33 It can be hydroxyl or alkoxy, n 32 Can be 0.

[0089] The aromatic dicarboxylic acid-based compound may further include an aromatic dicarboxylic acid component in addition to the furandicarboxylic acid-based compound.

[0090] The aromatic dicarboxylic acid may be an aromatic dicarboxylic acid having 8 to 20 carbon atoms, for example, an aromatic dicarboxylic acid having 8 to 14 carbon atoms or a mixture thereof, and may be isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid such as 2,6-naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbene dicarboxylic acid or 2,5-thiophene dicarboxylic acid, etc. Terephthalic acid includes dicarboxylic acids such as terephthalic acid, alkyl esters thereof (lower alkyl esters having 1 to 4 carbon atoms such as monomethyl ester, monoethyl ester, dimethyl ester, diethyl ester or dibutyl ester) and / or acid anhydrides thereof, and may react with a diol component to form a dicarboxylic acid moiety such as a terephthaloyl moiety.

[0091] Aliphatic diol compounds can provide excellent compatibility and elongation properties to polyester resins.

[0092] The aliphatic diol-based compound may be a compound represented by Chemical Formula 4.

[0093] Chemical formula 4:

[0094]

[0095] In chemical formula 4, A11 It is a straight-chain or branched divalent aliphatic hydrocarbon group having 1 to 15 carbon atoms.

[0096] As an example, the aliphatic diol compound may include aliphatic diol compounds having carbon atoms of 2 to 20, for example, aliphatic diol compounds having carbon atoms of 2 to 12. Such aliphatic diol compounds may be, for example, linear, branched or cyclic aliphatic diol components such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol (1,2-propylene glycol, 1,3-propylene glycol, etc.), 1,4-butanediol, pentanediol, hexanediol (1,6-hexanediol, etc.), neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and tetramethylcyclobutanediol.

[0097] In particular, the aliphatic diol compound may be ethylene glycol or 1,4-butanediol. In this case, in Chemical Formula 4, A 11 It may be a C2 alkylene group (ie, ethylene group) or a C4 alkylene group (ie, butylene group).

[0098] In the esterification step, an aromatic dicarboxylic acid compound is reacted with an aliphatic diol compound to prepare an aromatic oligomer with a low degree of polymerization.

[0099] The molar ratio of the aromatic dicarboxylic acid compound to the aliphatic diol compound may be 1:1.5 to 1:5.0. When the molar content of the aliphatic diol compound is too large compared to the molar content of the aromatic dicarboxylic acid compound, the reaction rate may be slowed down or the productivity of the resin may be reduced, and when the molar content of the aliphatic diol compound is too small, unreacted aromatic dicarboxylic acid components may remain, thereby generating impurities and possibly reducing the transparency of the resin.

[0100] An ether crosslinking agent may be added during the esterification reaction. Alternatively, a crosslinking agent may be added during the polymerization step.

[0101] Ether crosslinking agents, as crosslinking agents containing ether groups (ROR), can react with the ends of oligomers generated in the esterification reaction or polymerization step, thereby providing an end capping agent (Ending capper) effect while increasing the reaction rate, thereby achieving a polyester resin with excellent color.

[0102] The ether-based cross-linking agent is represented by Chemical Formula 2.

[0103] Chemical formula 2:

[0104]

[0105] In the chemical formula 2, the A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

[0106] As an example, the A 21 and A 22 They may be the same or different and may each independently be a linear or branched aliphatic hydrocarbon group having 1 to 5 carbon atoms substituted with a hydroxy group.

[0107] The Chemical Formula 2 may include Chemical Formula 2A, Chemical Formula 2B, Chemical Formula 2C, Chemical Formula 2D, or a combination thereof.

[0108] Chemical formula 2A:

[0109]

[0110] Chemical formula 2B:

[0111]

[0112] Chemical formula 2C:

[0113]

[0114] Chemical Formula 2D:

[0115]

[0116] For example, the cross-linking agent may be added in the esterification reaction step at a time when 40 wt % or more, for example, 50 wt % or more, 80 wt % or more, or 90 wt % or more of oligomers are prepared relative to 100 wt % of the total content of the oligomers formed in the esterification reaction step, or in the polymerization step at a time when 30 wt % or less, for example, 20 wt % or less, or 10 wt % or less of polyester is prepared relative to 100 wt % of the total content of the polyester prepared in the polymerization step.

[0117] The amount of the crosslinking agent added can be 10 ppm to 5000 ppm based on 1 kg of the polyester resin as the final polymer, for example, 10 ppm to 3000 ppm, 100 ppm to 3000 ppm or 300 ppm to 3000 ppm, for example, 100 ppm to 5000 ppm, 100 ppm to 3000 ppm, 500 ppm to 3000 ppm, 1000 ppm to 3000 ppm or 1000 ppm to 2000 ppm.

[0118] As the most specific example, the input amount of the crosslinking agent can be 100 ppm to 2000 ppm based on 1 kg of the polyester resin as the final polymer. When the input amount of the crosslinking agent is less than 100 ppm, the terminal acid value is high, so when it is commercialized (manufacturing films, bottles, etc.), the brittleness is reduced. When it is greater than 2000 ppm, the elongation is low, resulting in easy breakage. Based on 1 kg of the polyester resin as the final polymer, when the input amount of the crosslinking agent is less than 300 ppm, the terminal acid value is high, so when it is commercialized (manufacturing films, bottles, etc.), the brittleness is reduced. When it is greater than 3000 ppm, the elongation is low, resulting in easy breakage.

[0119] Additionally, a heat stabilizer may be further added during the esterification reaction.

[0120] As an example, the heat stabilizer may be added at a time when 10 wt % to 90 wt %, for example, 15 wt % to 80 wt %, or 20 wt % to 70 wt % of the oligomers are prepared relative to 100 wt % of the total content of the oligomers formed in the esterification reaction step. By adding the heat stabilizer at the above time, the reaction can be stably carried out and the acid value of the polyester resin finally produced can be reduced.

[0121] The heat stabilizer may include, for example, phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trimethyl phosphoacetate, triethyl phosphoacetate, or a mixture thereof.

[0122] In the esterification reaction step, the amount of the heat stabilizer added may be 5 ppm to 250 ppm, for example, 10 ppm to 220 ppm, 15 ppm to 200 ppm, or 20 ppm to 180 ppm, based on the phosphorus (P) element. In addition, the amount of the heat stabilizer added may be 0.01 to 1.00 parts by weight, for example, 0.02 to 0.90 parts by weight, 0.03 to 0.70 parts by weight, or 0.05 to 0.50 parts by weight, relative to 100 parts by weight of the aromatic dicarboxylic acid.

[0123] When the content of the heat stabilizer is too large, the activity of the catalyst will decrease, so the reaction time will be prolonged, the reaction conversion rate will be reduced, and the acid value of the final polymer will increase. When the content of the heat stabilizer is too small, the color and heat resistance of the chip will deteriorate.

[0124] The esterification reaction can be carried out by simultaneously adding aliphatic diol compounds and aromatic dicarboxylic acid compounds. Alternatively, the esterification reaction can be carried out in accordance with a primary esterification reaction and a secondary esterification reaction. The secondary esterification reaction can be carried out at a temperature higher than that of the primary esterification reaction. When the primary esterification reaction and the secondary esterification reaction are carried out, a heat stabilizer or a crosslinking agent can be added in the secondary esterification reaction step.

[0125] The esterification reaction step can be carried out in a nitrogen (N2) atmosphere at a temperature range of 160°C to 260°C for 1 hour to 8 hours. The esterification reaction step can be appropriately adjusted according to the raw material ratio, the specific characteristics of the target polyester resin, etc. For example, the esterification reaction step can be carried out in a temperature range of 180°C or more, 160°C or more, 170°C or more, or 180°C or more and 260°C or less, 240°C or less, or 220°C or less. In addition, the esterification reaction step can be carried out for 1 hour or more, 1.5 hours or more, or 2 hours or more and 8 hours or less, 7 hours or less, or 6 hours or less.

[0126] When the temperature, pressure, reaction time, etc. of the esterification reaction step are less than their respective ranges, the reaction yield is low, or the reaction cannot proceed sufficiently, and thus the physical properties of the polyester resin finally produced are reduced. When the temperature, pressure, reaction time, etc. of the esterification reaction are greater than their respective ranges, the appearance of the produced polyester resin is more likely to turn yellow, or depolymerization reaction may occur, and thus the polyester resin cannot be synthesized in the preparation method.

[0127] The esterification reaction step can be carried out in a batch or continuous manner.

[0128] On the other hand, the esterification step can also be carried out in the presence of an esterification catalyst. In particular, an esterification catalyst can be added to the esterification step to improve the reaction rate from the initial stage of the reaction and shorten the time the polyester resin is heated.

[0129] The esterification reaction catalyst may use titanium compounds, germanium compounds, aluminum compounds, tin compounds or mixtures thereof.

[0130] Titanium compounds can be, for example, tetraethyl titanate, acetyl tripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octanediol titanate, lactic acid titanate, triethanolamine titanate, acetylacetonate titanate, ethyl acetoacetate titanate, isostearyl titanate, titanium dioxide, titanium dioxide / silicon dioxide copolymer, titanium dioxide / zirconium dioxide copolymer, etc.

[0131] Tin compounds may be, for example, tributyltin, tin diacetate, tin dioctoate, tin dilaurate, or dibutyltin dilaurate.

[0132] Alternatively, the compound represented by Chemical Formula 5 may be used as the esterification reaction catalyst.

[0133] Chemical formula 5:

[0134] C a H b O c P d M e

[0135] In Chemical Formula 5, a is an integer of 1 to 15, b is an integer of 2 to 25, c is an integer of 1 to 5, d is an integer of 0 to 5, e is an integer of 1 to 5, and M is Ti, Co, Zn, Mn, Sn, Sb, or a combination thereof.

[0136] In the polyester resin to be synthesized, 10ppm to 1000ppm of the esterification reaction catalyst can be used based on the central metal atom. When the content of the esterification reaction catalyst is too small, the efficiency of the esterification reaction is difficult to significantly improve, and the amount of reactants that do not participate in the reaction will increase significantly. In addition, when the content of the esterification reaction catalyst is too large, the appearance properties of the polyester resin produced will be reduced. In addition, when the content of the esterification reaction catalyst is too large, the polyester resin produced will turn yellow and the appearance properties will be reduced.

[0137] In the polymerization step, the oligomer is polymerized. As an example, the polymerization step may include the following steps: a prepolymerization step of prepolymerizing the oligomer; and a polycondensation step of subjecting the prepolymerized polymer to a polycondensation reaction.

[0138] In the prepolymerization step, the oligomer is prepolymerized to prepare a polymer having a higher degree of polymerization than the product of the esterification reaction.

[0139] The prepolymerization step, the polycondensation step, or the polymerization step including both may be performed in the presence of a catalyst. The polymerization catalyst may be a compound represented by Chemical Formula 6.

[0140] Chemical formula 6:

[0141] C a H b O c P d Ti e

[0142] In Chemical Formula 6, a is an integer of 15 to 150, b is an integer of 20 to 300, c is an integer of 5 to 40, d is an integer of 0 to 5, and e is an integer of 1 to 5. In this case, c / e≥4 may be satisfied.

[0143] For example, in Chemical Formula 6, a may be an integer of 44 to 100, b may be an integer of 98 to 194, c may be an integer of 8 to 18, d may be an integer of 2 to 4, and 5≤c / e≤18 may be satisfied.

[0144] As an example, when the polymerization reaction catalyst satisfies the above-mentioned conditions a, b, c, d, e, c / e and contains a catalyst containing a -Ti-OP- bond, a catalyst containing a -Ti-PO- bond, or a catalyst containing a -Ti-O- bond, the relationship between thermal discoloration and molecular weight (trade-offs) can be eliminated.

[0145] As an example, the compound represented by Chemical Formula 6 may include compounds represented by Chemical Formulas 61 to 63.

[0146] Chemical formula 61:

[0147]

[0148] Chemical formula 62:

[0149]

[0150] Chemical formula 63:

[0151] (C8H 17 -O-)4-Ti(P-(OC 13 H 27 )2OH]2

[0152] In the polyester resin to be synthesized, 2ppm to 100ppm of the polymerization catalyst can be used based on the central metal atom. When the content of the polymerization catalyst is too small, the amount of reactants that do not participate in the reaction will increase significantly. When the content of the polymerization catalyst is too large, it will remain as inert particles, thereby reducing the physical properties of the polymer.

[0153] At this time, the weight ratio of the polymerization catalyst to the esterification catalyst may be 0.015 to 0.3, for example, 0.015 to 0.2. When the polymerization catalyst is less than 0.015 parts by weight relative to 1 part by weight of the esterification catalyst, the polymerization reaction rate is reduced, and therefore, the reaction time is delayed. When the polymerization catalyst is greater than 0.3 parts by weight, side reactions may cause the reaction product to discolor.

[0154] On the other hand, a heat stabilizer may also be used during the prepolymerization process. When a heat stabilizer is used, it is possible to minimize not only the thermal discoloration during the prepolymerization process but also the thermal discoloration during the subsequent polycondensation reaction.

[0155] Specifically, the heat stabilizer can be trimethyl phosphonoacetate, triethyl phosphonoacetate, phosphoric acid, phosphorous acid, polyphosphoric acid, trimethyl phosphate (TMP), triethyl phosphate, trimethyl phosphine, triphenylphosphine or a phosphorus-based heat stabilizer containing a mixture thereof.

[0156] Prepolymerization can be carried out under temperature control conditions (Thermal pre-Condensation).

[0157] Specifically, the prepolymerization may include the following steps: a step of raising the temperature to a temperature range of 220° C. to 260° C.; and a step of maintaining the reached temperature and prepolymerizing the product of the second esterification reaction.

[0158] Furthermore, when the temperature is raised, after the pressure is reduced to 0 atm to 0.3 atm, while the achieved temperature is maintained, the achieved pressure may be maintained.

[0159] The prepolymerization step is a step of changing from normal pressure to vacuum before the polycondensation reaction (vacuum) described later, and may be a step of changing from normal pressure (1 atm) to vacuum (0 atm) in stages. When the prepolymerization step is omitted, the product of the esterification reaction volatilizes during the rapid change to the vacuum state, causing a sudden boiling phenomenon, resulting in a decrease in the yield of the final polyester resin and an adverse effect on the physical properties.

[0160] After the prepolymerization, the prepolymerized polymer is subjected to a polycondensation reaction.

[0161] The polycondensation step may be performed in a vacuum atmosphere at a temperature ranging from 220° C. to 300° C. and a pressure ranging from 0.8 torr to 0.4 torr for 1 to 7 hours.

[0162] The polycondensation reaction step can be carried out in a state where the vacuum degree is slightly higher than 0 atm. The vacuum degree is measured using a vacuum gauge, and the polymerization is usually carried out in the range of 0.8 torr to 0.4 torr.

[0163] When performing the polycondensation, a polycondensation catalyst may be used.

[0164] The polycondensation catalyst may be added to the product of the esterification reaction before the start of the polycondensation reaction, may be added to the mixture containing the diol component and the dicarboxylic acid component before the esterification reaction, or may be added in the middle of the esterification reaction step.

[0165] The polycondensation catalyst may use the compound represented by Chemical Formula 6, or a titanium compound, a germanium compound, an antimony compound, an aluminum compound, a tin compound, or a mixture thereof.

[0166] Titanium compounds can be, for example, tetraethyl titanate, acetyl tripropyl titanate, tetrapropyl titanate, tetrabutyl titanate, polybutyl titanate, 2-ethylhexyl titanate, octanediol titanate, lactic acid titanate, triethanolamine titanate, acetylacetonate titanate, ethyl acetoacetate titanate, isostearyl titanate, titanium dioxide, titanium dioxide / silicon dioxide copolymer, titanium dioxide / zirconium dioxide copolymer, etc.

[0167] The germanium compound may be, for example, germanium dioxide (GeO), germanium tetrachloride (GeCl), germanium ethyleneglycoxide, germanium acetate, copolymers thereof, mixtures thereof, and the like.

[0168] Optionally, the method for preparing the polyester resin may further include the step of adding a chain extender after the polymerization step to prepare a chain-extended polyester resin.

[0169] The molecular weight is increased by the chain extension reaction, thereby making it possible to prepare a polyester resin having desired physical properties.

[0170] The chain extender may be a polyisocyanate compound, an aromatic amine compound, etc. The polyisocyanate compound may include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, triphenylmethane triisocyanate or a mixture thereof, and the aromatic amine compound may be DETDA80 product of Lonza Company, which is a mixture of 3,5-diethyl-2,4-diaminotoluene and 3,5-diethyl-2,6-diaminotoluene in a weight ratio of 20:80.

[0171] Polyester resin

[0172] The polyester resin of another embodiment includes a copolymer containing a repeating unit represented by Chemical Formula 1, and is cross-linked by an ether cross-linking agent represented by Chemical Formula 2, and has a terminal acid value of 5 meq / kg to 20 meq / kg.

[0173] Chemical formula 1:

[0174]

[0175] Chemical formula 2:

[0176]

[0177] In the chemical formula 1, the A 11 is a straight or branched divalent aliphatic hydrocarbon group having 1 to 15 carbon atoms, wherein R 11 is a halogen group, a hydroxyl group, an alkoxy group or an alkyl group, wherein n 11 is the molar ratio of the repeating units, the n 12 is an integer from 0 to 2,

[0178] In the chemical formula 2, the A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

[0179] As an example, the A 21 and A 22 They may be the same or different and may each independently be a linear or branched aliphatic hydrocarbon group having 1 to 5 carbon atoms substituted with a hydroxy group.

[0180] The Chemical Formula 2 may include Chemical Formula 2A, Chemical Formula 2B, Chemical Formula 2C, Chemical Formula 2D, or a combination thereof.

[0181] Chemical formula 2A:

[0182]

[0183] Chemical formula 2B:

[0184]

[0185] Chemical formula 2C:

[0186]

[0187] Chemical Formula 2D:

[0188]

[0189] Based on 1 kg of the copolymer, the amount of the ether cross-linking agent added can be 10 ppm to 5000 ppm, for example, 10 ppm to 3000 ppm, 100 ppm to 3000 ppm or 300 ppm to 3000 ppm, for example, 100 ppm to 5000 ppm, 100 ppm to 3000 ppm, 500 ppm to 3000 ppm, 1000 ppm to 3000 ppm or 1000 ppm to 2000 ppm.

[0190] As the most specific example, the input amount of the crosslinking agent can be 100 ppm to 2000 ppm based on 1 kg of the polyester resin as the final polymer. When the input amount of the crosslinking agent is less than 100 ppm, the terminal acid value is high, so when it is commercialized (manufacturing films, bottles, etc.), the brittleness is reduced. When it is greater than 2000 ppm, the elongation is low, resulting in easy breakage. The number average molecular weight (Mn) of the polyester resin can be 20,000 g / mol to 50,000 g / mol, for example, 23,000 g / mol to 35,000 g / mol, 23,000 g / mol to 30,000 g / mol, 23,000 g / mol to 27,000 g / mol or 23,000 g / mol to 25,000 g / mol.

[0191] When the number average molecular weight of the polyester resin is less than 20,000 g / mol, film forming for use as a packaging material is difficult and the desired modulus cannot be achieved. On the other hand, when the number average molecular weight exceeds 50,000 g / mol, the viscosity increases, resulting in reduced productivity and yield.

[0192] According to the CIE 1976 L*a*b* color system, the L* value of the polyester resin may be 94 or more, the a* value may be -0.5 to 0, and the b* value may be 5.0 or less.

[0193] For example, according to the CIE 1976 L*a*b* color system, the L* value may be 96.4 or more, the a* value may be -0.5 to 0, and the b* value may be 4.1 or less.

[0194] For example, the method for measuring the polyester resin colorimeter is as follows: 2 g of the polyester resin sample is dissolved in 20 mL of hexafluoroisopropanol (HFIP) (0.1 g / mL in HFIP). The sample solution is measured using a CM-3700A product from Konica Minolta in a Tuartz cell dedicated to solution colorimeter measurement.

[0195] The higher the L* value, the closer to white the color can be. The L* value of the polyester resin can be 94 or more or 96.4 or more and 100 or less, 99 or less, or 97.5 or less. When the L* value is less than 94, problems such as low transmittance or fogging may occur during film formation.

[0196] The smaller the a* value is within the range below 0, the lighter the red color and the darker the green color. The a* value of the polyester resin may be below 0, below -0.03, below -0.06, or below -0.1 and above -0.5, above -0.52, above -0.54, or above -0.56. When the a* value is greater than 0, the film may be red.

[0197] The b* value is within the range of 5.0 or less, and the smaller the value, the lighter the yellow and the darker the blue. The b* value of the polyester resin can be 5.0 or less or 4.1 or less and 0 or more, 1 or more, or 2.2 or more. When the b* value is greater than 5.0, the color of the film may be problematic.

[0198] The color characteristics of polyester resin can be adjusted by the monomer reaction sequence and monomer usage during its preparation process.

[0199] The difference between the intrinsic viscosity values ​​of the polyester resin measured at 35° C. and 25° C., i.e., ΔIV, may be 0.2 dL / g to 1.6 dL / g, for example, 0.65 dL / g to 0.67 dL / g. When the above range is satisfied, film-forming processing for use as a packaging material is easy, and the desired modulus, productivity, and yield can be achieved.

[0200] The terminal acid value of the polyester resin may be 5 meq / kg to 20 meq / kg, for example, the terminal acid value may be 8 meq / kg to 20 meq / kg, 8 meq / kg to 15 meq / kg or 8 meq / kg to 10 meq / kg. The terminal acid value indicates the content of COOH at the end of the polymer, and the terminal acid value of the polyester may be measured by titration according to the revised ASTM D7409. Specifically, 1 g of the sample is accurately quantified and placed in a vial. 20 mL of o-cresol reagent is pipetted using a pipette. Stir in a dissolving tank at 100° C. for 1 hour to dissolve it. The solution is transferred to a 100 mL beaker, after which the inner wall of the vial is cleaned with 50 mL of chloroform and added to the beaker. 2 to 3 drops of methylene blue and methylene red reagents are added, and titration is performed using a 0.04 N KOH (alcoholic) solution. When the terminal acid value of the polyester resin is greater than 15 meq / kg, brittleness may occur during the manufacture of films or bottles.

[0201] The glass transition temperature (Tg) of the polyester resin may be 85°C to 100°C, for example, 87°C to 94°C.

[0202] The melting temperature (Tm) of the polyester resin may be 200°C to 240°C, for example, 205°C to 220°C.

[0203] The elongation (Elongation, %) of the polyester resin may be 130% or more, for example, 150% or more or 180% or more.

[0204] On the other hand, the polyester resin is prepared by the above-mentioned preparation method, and therefore, based on the phosphorus (P) element, it can further contain 0.1ppm to 100ppm, for example, 0.1ppm to 50ppm, 0.1ppm to 20ppm or 1ppm to 20ppm of a heat stabilizer. When the content of the heat stabilizer is less than 0.1ppm, the polymer will change color, and when it is greater than 100ppm, the activity of the polymerization catalyst is reduced, the reaction speed is slowed down, and the viscosity of the polymer is reduced.

[0205] Hereinafter, the present invention will be described with reference to examples. The examples described below are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[0206] [Preparation Example: Preparation of polyester resin]

[0207] (Example 1-1)

[0208] Into the hopper of a 2L autoclave reactor, 857 g, 5.5 molar parts of 2,5-furandicarboxylic acid (FDCA) and 511 g, 8.3 molar parts of ethylene glycol (EG) were added to obtain a total theoretical yield of 1 kg of polyester.

[0209] Then, based on the tin metal, 10 ppm of TBT (Tributyltin) catalyst was added, and based on 1 kg of the final polymer, 1000 ppm of DPE (Dipentaerythritol) represented by the chemical formula 2C was added as a crosslinking agent, and an esterification reaction was carried out at a temperature of 200° C. and in a nitrogen atmosphere for 3 hours.

[0210] Chemical formula 2C:

[0211]

[0212] When the esterification reaction is completed and the clearing point (C;ear point) is reached so that the oligomer becomes transparent, phosphoric acid (PA) (50 ppm based on phosphorus element) is added as a heat stabilizer to prepare the oligomer.

[0213] In the prepolymerization, while the temperature inside the reactor was raised to 260° C. over 1 hour, the pressure inside the reactor was gradually reduced from 1 atm to 0 atm over 1 hour using a vacuum pump to carry out prepolymerization.

[0214] The reaction was carried out for 4 hours at a temperature range of 250° C. and a high vacuum of less than 0.8 torr. When the load received by the torque meter of the autoclave reached the required load, the autoclave was drained to obtain the polyester resin of Example 1-1.

[0215] (Example 1-2)

[0216] A polyester resin was obtained in the same manner as in Example 1-1 except that 2000 ppm of a crosslinking agent was added based on 1 kg of the final polymer as shown in Table 1.

[0217] (Example 2-1)

[0218] A polyester resin was obtained in the same manner as in Example 1-1 except that DPG (dipropylene glycol) represented by Chemical Formula 2A, Chemical Formula 2B or a mixture thereof was added as a crosslinking agent as shown in Table 1.

[0219] Chemical formula 2A:

[0220]

[0221] Chemical formula 2B:

[0222]

[0223] (Example 2-2)

[0224] A polyester resin was obtained in the same manner as in Example 2-1 except that 2000 ppm of a crosslinking agent was added based on 1 kg of the final polymer as shown in Table 1.

[0225] (Example 3-1)

[0226] A polyester resin was obtained in the same manner as in Example 1-1 except that DTP (Di(trimethylolpropane): di(trimethylolpropane)) represented by Chemical Formula 2D was added as a crosslinking agent as shown in Table 1.

[0227] Chemical Formula 2D:

[0228]

[0229] (Example 3-2)

[0230] A polyester resin was obtained in the same manner as in Example 3-1 except that 2000 ppm of a crosslinking agent was added based on 1 kg of the final polymer as shown in Table 1.

[0231] (Comparative Example 1)

[0232] A polyester resin was obtained in the same manner as in Example 1-1 except that no crosslinking agent was added as shown in Table 1.

[0233] (Comparative Example 2)

[0234] A polyester resin was obtained in the same manner as in Example 1-1 except that no crosslinking agent was added and 300 ppm of Sb2O3 was added as a catalyst based on the Sb-based metal as shown in Table 1.

[0235] (Comparative Examples 3 to 5)

[0236] A polyester resin was obtained in the same manner as in Example 1-1 except that the type of the crosslinking agent added was not an ether crosslinking agent but pentaerythritol, glycerin and trihydroxypropane as shown in Table 1.

[0237] Table 1:

[0238]

[0239] [Experimental Example 1: Measurement of the color, intrinsic viscosity difference and terminal acid value of polyester resin]

[0240] The color, intrinsic viscosity difference and terminal acid value of the polyester resin samples prepared in each of the examples and comparative examples were measured by the following methods, and the results are shown in Table 2.

[0241] 1) Color characteristics: Using a chip colorimeter manufactured by Nippon Denshoku (sa-4000), the values ​​of L*, a*, and b* were measured under the following conditions.

[0242] 2 g of a polyester resin sample was dissolved in 20 mL of hexafluoroisopropanol (HFIP) (0.1 g / mL in HFIP), and the sample solution was measured using a CM-3700A product manufactured by Konica Minolta in a Tuartz cell dedicated to solution colorimetry.

[0243] 2) Difference in intrinsic viscosity (ΔIV): Dissolve 0.5 g of the sample in 10 mL of a 1:1 (v:v) solution of phenol and tetrachloroethane. Measure the IV at 25°C and 35°C using an Ostwald viscometer and calculate the difference (ΔIV).

[0244] 3) Terminal acid value (meq / kg): The terminal acid value of polyester can be measured by titration according to the revised ASTM D7409. Specifically, 1 g of the sample is accurately quantified and placed in a vial. 20 mL of o-cresol (O-Cresol) reagent is transferred using a pipette. Stir in a dissolution tank at 100°C for 1 hour to dissolve it. The solution is transferred to a 100 mL beaker, after which 50 mL of chloroform is used to clean the inner wall of the vial and added to the beaker. 2 to 3 drops of methylene blue and methylene red reagents are added, and titration is performed using a 0.04 N KOH (alcoholic) solution.

[0245] [Experimental Example 2: Tg, DEG content, number average molecular weight]

[0246] 1) Glass transition temperature (Tg): DSC from TA Instruments was used to measure the temperature from room temperature to 300° C. at 20° C. / min under N 2 and 20 psi.

[0247] 2) Measurement of DEG (diethylene glycol) content: Agilent GC-MS, Rtx-5MS (0.25 μm × 0.25 mm × 30 m) column was used for measurement and displayed in %. The DEG content represents a processing influence factor. The higher the content, the lower the Tm, and the easier it is to pyrolyze during processing, so the processability is poor.

[0248] 3) Number average molecular weight (Mn): Mn was measured using gel permeation chromatography (GPC).

[0249] Table 2:

[0250]

[0251] From the results in Table 2, it can be confirmed that the terminal acid value of the polyester resin of the embodiment is as low as 8 meq / kg to 10 meq / kg, and the b* value is 5.0 or less, so the terminal acid value is reduced and thermal discoloration is suppressed. On the contrary, it can be confirmed that the terminal acid value of the polyester resin of Comparative Examples 1 and 2 is greater than 25 meq / kg, and the b* value is greater than 5.5, and the terminal acid value of the polyester resin of Comparative Examples 3 to 5 is greater than 11 meq / kg, and the b* value is 4.9 or more, so the effect of reducing the terminal acid value or suppressing thermal discoloration cannot be achieved. In addition, it can be confirmed that the elongation of the polyester resin of the embodiment is significantly higher than that of the comparative example, so the mechanical properties are also significantly excellent.

[0252] The above describes in detail several preferred embodiments of the present invention, but the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present invention defined in the attached claims also fall within the scope of the present invention.

[0253] Industrial Applicability

[0254] The present invention relates to a polyester resin and a preparation method thereof. In one embodiment, the terminal acid value of the polyester resin is reduced, thermal discoloration is suppressed, and mechanical properties are improved. In another embodiment, the preparation method of the polyester resin can reduce the terminal acid value of the polyester resin to improve the physical properties, suppress thermal discoloration of the polymer, and improve the mechanical properties.

Claims

1. A polyester resin, characterized in that A copolymer comprising a repeating unit represented by Chemical Formula 1, and cross-linked by an ether cross-linking agent represented by Chemical Formula 2, The terminal acid value is 5meq / kg~20meq / kg, Chemical formula 1: Chemical formula 2: In the chemical formula 1, The A 11 is a straight-chain or branched divalent aliphatic hydrocarbon group having 1 to 15 carbon atoms, The R 11 is a halogen group, a hydroxyl group, an alkoxy group or an alkyl group, The 11 is the number of repetitions of the repeating unit, The 12 is an integer from 0 to 2, In the chemical formula 2, The A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

2. The polyester resin according to claim 1, characterized in that The chemical formula 2 includes chemical formula 2A, chemical formula 2B, chemical formula 2C, chemical formula 2D or a combination thereof, Chemical formula 2A: Chemical formula 2B: Chemical formula 2C: Chemical Formula 2D:

3. The polyester resin according to claim 1, characterized in that The terminal acid value of the polyester resin is 6 meq / kg to 11 meq / kg.

4. The polyester resin according to claim 1, characterized in that The difference between the intrinsic viscosity values ​​of the polyester resin measured at 35° C. and 25° C., namely, ΔIV, is 0.2 dL / g to 1.6 dL / g.

5. The polyester resin according to claim 1, characterized in that According to a CIE 1976 L*a*b* colorimeter, the polyester resin has an L* value of 94 or more and a b* value of 5.0 or less.

6. The polyester resin according to claim 1, characterized in that The polyester resin has a glass transition temperature Tg of 85°C to 100°C and a melting temperature Tm of 200°C to 240°C.

7. The polyester resin according to claim 1, characterized in that The elongation of the polyester resin is greater than 130%.

8. A method for preparing a polyester resin, characterized in that: The steps include: an esterification reaction step of reacting an aromatic dicarboxylic acid compound including a furandicarboxylic acid compound, an aliphatic diol compound, and an ether crosslinking agent represented by Chemical Formula 2 to prepare an oligomer; as well as a polymerization step of polymerizing the oligomer to prepare a polyester resin, Wherein, the terminal acid value of the polyester resin is 5meq / kg to 20meq / kg, Chemical formula 2: In the chemical formula 2, The A 21 and A 22 Each is independently a linear or branched aliphatic hydrocarbon group having 1 to 10 carbon atoms which is substituted with a hydroxy group.

9. The method for preparing a polyester resin according to claim 8, characterized in that: Based on 1 kg of the polyester resin, 10 ppm to 5000 ppm of the ether crosslinking agent is added.

10. The method for preparing a polyester resin according to claim 8, characterized in that: The chemical formula 2 includes chemical formula 2A, chemical formula 2B, chemical formula 2C, chemical formula 2D or a combination thereof, Chemical formula 2A: Chemical formula 2B: Chemical formula 2C: Chemical Formula 2D:

11. The method for preparing a polyester resin according to claim 8, characterized in that: The aromatic dicarboxylic acid compound further includes isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, 4,4'-stilbene dicarboxylic acid, 2,5-thiophene dicarboxylic acid or a mixture thereof.

12. The method for preparing a polyester resin according to claim 8, characterized in that: The furan dicarboxylic acid compound is a compound represented by Chemical Formula 3, Chemical formula 3: In the chemical formula 3, The R 31 is a halogen group, a hydroxyl group, an alkoxy group or an alkyl group, The R 32 and R 33 are independently hydroxyl or alkoxy, The 32 An integer from 0 to 2.

13. The method for preparing a polyester resin according to claim 8, characterized in that: The aliphatic diol compound is a compound represented by Chemical Formula 4, Chemical formula 4: In the chemical formula 4, The A 11 It is a straight-chain or branched divalent aliphatic hydrocarbon group having 1 to 15 carbon atoms.

14. The method for preparing a polyester resin according to claim 8, characterized in that: In the esterification reaction step, the molar ratio of the aromatic dicarboxylic acid compound to the aliphatic diol compound is 1:1.5 to 1:5.

0.

15. The method for preparing a polyester resin according to claim 8, characterized in that: The polymerization step comprises the following steps: a prepolymerization step of prepolymerizing the oligomer; and The polycondensation step is to subject the polymer formed by the prepolymerization to a polycondensation reaction.

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