Polyester polymer, its production method, and catalyst system

Abstract

The present invention relates to a polyester polymer comprising a polymer matrix containing polyester repeat units; and a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid remaining in the polymer matrix; and a method for producing the same and a catalyst system.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0168706, filed December 6, 2022, and Korean Patent Application No. 10-2023-0065848, filed May 22, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a polyester polymer that can significantly reduce polymerization time and increase productivity while maintaining excellent physical properties, and to a method for producing the same and a catalyst system. [Background technology]

[0003] Polyester polymers are commercially produced by a two-step reaction in which diols, dicarboxylic acids, or dicarboxylates are used as raw materials, and the reaction product is then subjected to esterification or ester exchange reaction, followed by polycondensation.

[0004] For example, polybutylene terephthalate (PBT), a widely known polyester polymer, is produced from 1,4-butylene glycol (BG) and terephthalic acid (TPA) as starting materials through esterification and condensation polymerization steps.

[0005] Meanwhile, in the polycondensation step, in order to improve productivity, a co-catalyst can be additionally used in addition to the main catalyst, and as such a co-catalyst, an alkali metal salt or an alkaline earth metal salt such as sodium acetate (Na-acetate), magnesium acetate (Mg acetate), or calcium acetate (Ca acetate) has been mainly used.

[0006] However, in the process using the existing cocatalyst, it is difficult to sufficiently shorten the polymerization time, and the productivity remains low, making it unsuitable for mass production.

[0007] Therefore, there is a need for a method for producing polyester polymers that can produce polyester polymers that maintain similar thermal and mechanical properties to conventional methods while shortening the polymerization time sufficiently to make them suitable for mass production. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a polyester polymer that can significantly reduce the polymerization time while maintaining excellent physical properties, thereby increasing productivity.

[0009] The present invention also provides a method for producing the polyester polymer.

[0010] The present invention further provides a catalyst system for use in producing the polyester polymer. [Means for solving the problem]

[0011] In order to solve the above problems, the present specification provides a polyester polymer including: a polymer matrix containing polyester repeating units; and a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid remaining in the polymer matrix.

[0012] The present specification also provides a method for producing a polyester polymer, comprising: a) an esterification reaction step of reacting a diol and a dicarboxylic acid or a derivative thereof in the presence of a catalyst and a co-catalyst; b) a first condensation polymerization step of adding a catalyst to the reaction mixture after the completion of step a) and carrying out condensation polymerization under reduced pressure to produce a prepolymer; and c) a second condensation polymerization step of condensing the prepolymer under a pressure condition lower than that of step b), wherein the co-catalyst comprises a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid.

[0013] Further provided herein is a catalyst system comprising a catalyst and a co-catalyst, wherein the co-catalyst comprises a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid.

[0014] The polyester polymer, its production method, and catalyst system according to specific embodiments of the invention will be described in more detail below.

[0015] In this specification, unless expressly stated otherwise, terminology is for the purpose of referring to particular embodiments only and is not intended to limit the invention.

[0016] As used herein, the singular forms "a," "an," and "the" include the plural forms as well, unless the context clearly dictates to the contrary.

[0017] As used herein, the meaning of "comprising" embodies certain properties, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other certain properties, regions, integers, steps, operations, elements, components, and / or groups.

[0018] In this specification, terms including ordinal numbers such as "first" and "second" are used to distinguish one component from another, and are not limited by the ordinal numbers. For example, within the scope of the present invention, a first component may be called a second component, and similarly, a second component may be called a first component.

[0019] In this specification, examples of the substituents are explained below, but the present invention is not limited to these.

[0020] As used herein, the term "substituted" means that another functional group is bonded in place of a hydrogen atom in a compound, and the substitution position is not limited as long as it is a position at which a hydrogen atom is substituted, i.e., a position at which a substituent can be substituted, and when two or more substituents are substituted, the two or more substituents may be the same or different.

[0021] As used herein, the term "substituted or unsubstituted" refers to a group selected from the group consisting of deuterium, halogen, cyano, nitro, hydroxy, carbonyl, ester, imide, amide, primary amino, carboxy, sulfonic acid, sulfonamide, phosphine oxide, alkoxy, aryloxy, alkylthioxy, arylthioxy, alkylsulfoxy, arylsulfoxy, silyl, boron, alkyl, cycloalkyl, alkenyl, aryl, aralkyl, aralkenyl, alkylaryl, alkoxysilylalkyl, arylphosphine, or heterocyclic groups containing one or more N, O, and S atoms, or a group in which two or more of the above-listed substituents are linked together. For example, a "substituent having two or more linked substituents" may be a biphenyl group. In other words, a biphenyl group may be an aryl group or may be interpreted as a substituent in which two phenyl groups are linked together.

[0022] In this specification, [ka] or [ka] means a bond that connects to another substituent, and a direct bond means that there is no other atom in the moiety represented by L.

[0023] In this specification, aromaticity refers to a property that satisfies the Huckels Rule, and according to the Huckels Rule, a compound can be defined as aromatic if it satisfies all of the following three conditions: 1) There must be 4n+2 electrons in complete conjugation due to vacant p-orbitals, unsaturated bonds, unpaired electron pairs, etc. 2) The 4n+2 electrons must form a planar isomer and form a ring structure. 3) All atoms of the ring must be able to participate in conjugation.

[0024] In this specification, aliphatic can be defined as anything that does not satisfy the above-mentioned aromaticity.

[0025] In this specification, the alkyl group is a monovalent functional group derived from an alkane, and may be linear or branched, and the number of carbon atoms in the linear alkyl group is not particularly limited, but is preferably 1 to 20. Furthermore, the number of carbon atoms in the branched alkyl group is 3 to 20. Exemplary alkyl groups include, but are not limited to, methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethylpropyl, 1,1-dimethylpropyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, 2,6-dimethylheptan-4-yl, and the like. The alkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

[0026] As used herein, a cycloalkyl group refers to a monovalent functional group derived from a cycloalkane, and may be monocyclic or polycyclic. It has 3 to 20 carbon atoms, but is not limited thereto. According to another embodiment, the cycloalkyl group has 3 to 10 carbon atoms. Specific examples include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, and bicyclo[2,2,1]heptyl. The cycloalkyl group may be substituted or unsubstituted. If substituted, examples of the substituent are as described above.

[0027] In this specification, the aryl group is a monovalent functional group derived from arene, and is not particularly limited. It preferably has 6 to 20 carbon atoms and may be a monocyclic aryl group or a polycyclic aryl group. The monocyclic aryl group may be, but is not limited to, a phenyl group, a biphenyl group, a terphenyl group, etc. The polycyclic aryl group may be, but is not limited to, a naphthyl group, an anthracenyl group, a phenanthryl group, a pyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group, etc. The aryl group may be substituted or unsubstituted. If substituted, examples of the substituent are as described above.

[0028] In this specification, an alkylene group is a divalent functional group derived from an alkane, and the above description of the alkyl group is applicable, except that it is a divalent functional group. For example, it may be linear or branched, and may be a methylene group, ethylene group, propylene group, isobutylene group, sec-butylene group, tert-butylene group, pentylene group, hexylene group, etc. The alkylene group may be substituted or unsubstituted, and if substituted, examples of the substituent are as described above.

[0029] In this specification, an arylene group is a divalent functional group derived from arene, and the above description of the aryl group is applicable, except that it is a divalent functional group. For example, it may be a phenylene group, biphenylene group, terphenylene group, naphthalene group, fluorenyl group, pyrenyl group, phenanthrenyl group, perylene group, tetracenyl group, anthracenyl group, etc. The arylene group may be substituted or unsubstituted, and if substituted, examples of the substituent are as described above.

[0030] In this specification, the cycloalkylene group is a divalent functional group derived from a cycloalkane, and the above description of the cycloalkyl group is applicable except that it is a divalent functional group. The cycloalkylene group may be substituted or unsubstituted, and if substituted, examples of the substituent are as described above.

[0031] In this specification, a derivative compound means a compound that has been modified from a certain organic compound by introducing a functional group, oxidation, reduction, atomic substitution, etc., within the limits that do not significantly change the structure and properties of the parent compound.

[0032] The present invention will now be described in more detail.

[0033] 1. Polyester polymer According to one embodiment of the invention, there is provided a polyester polymer comprising: a polymer matrix containing polyester repeating units; and a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid remaining in the polymer matrix.

[0034] The present inventors have confirmed through experiments that, as in the polyester polymer of the above embodiment, by adding a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid as co-catalysts during synthesis of the polyester polymer, the production efficiency of the polyester polymer can be improved while maintaining excellent physical properties, and have completed the invention.

[0035] The monometallic salt of a polyvalent inorganic acid and the multimetallic salt of a polyvalent inorganic acid can be added as a co-catalyst together with the diol monomer, the dicarboxylic acid or its derivative, and the main catalyst in the synthesis of the polyester polymer, and some or all of them may remain in the final synthesized polyester polymer.

[0036] Specifically, the polyester polymer may include a polymer matrix containing polyester repeating units. The polyester polymer may include both homopolymers and copolymers depending on the type of polyester repeating unit. That is, the polymer matrix may include at least one type of polyester repeating unit, or two or more types of polyester repeating units. When the polymer matrix contains one type of polyester repeating unit, a polyester homopolymer is formed, and when the polymer matrix contains two or more types of polyester repeating units, a polyester copolymer is formed.

[0037] The polyester homopolymer is a polyester polymer synthesized by reacting one diol with a dicarboxylic acid or one derivative thereof, and the polyester copolymer may be a polyester polymer synthesized by reacting one diol with two or more dicarboxylic acids or derivatives thereof, or a polyester polymer synthesized by reacting two or more diols with a dicarboxylic acid or one derivative thereof, or a polyester polymer synthesized by reacting two or more diols with two or more dicarboxylic acids or derivatives thereof.

[0038] The polyester repeating unit means a repeating unit containing a polyester functional group in the repeating unit structure, and specifically, may have a structure represented by the following Chemical Formula 1.

[0039] [ka]

[0040] In the above chemical formula 1, R1 is one of an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 3 to 10 carbon atoms, or an arylene group having 6 to 20 carbon atoms, and R2 is an alkylene group having 1 to 10 carbon atoms.

[0041] As a more specific example, in the above Chemical Formula 1, R1 may be an arylene group having 6 to 20 or 6 to 8 carbon atoms, and R2 may be an alkylene group having 1 to 10 or 1 to 5 carbon atoms. As one example, in the above Chemical Formula 1, R1 may be a phenylene group, and R2 may be a butylene group.

[0042] The polyester repeating unit may include a reaction product of a dicarboxylic acid or a derivative thereof and a diol. Examples of the dicarboxylic acid or a derivative thereof include terephthalic acid, which is an aromatic dicarboxylic acid, and examples of the diol include 1,4-butanediol, which is an aliphatic diol.

[0043] Meanwhile, the polyester polymer may contain a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid remaining in the polymer matrix. The monometallic salt of a polyvalent inorganic acid and the multimetallic salt of a polyvalent inorganic acid may be added as a co-catalyst together with the diol monomer, the dicarboxylic acid or its derivative, and the main catalyst during the synthesis of the polyester polymer, and some or all of them may remain in the final synthesized polyester polymer.

[0044] This can be confirmed by inductively coupled plasma (ICP) analysis of the final synthesized polyester polymer. Specifically, the presence of two polyvalent inorganic acid metal salt cocatalysts remaining in the polyester polymer can be confirmed by quantitative analysis of metal elements (e.g., Na and S) using ICP. Furthermore, the content and ratio of the two polyvalent inorganic acid metal salt cocatalysts can be confirmed by ion chromatography analysis or a combination of ICP and ion chromatography.

[0045] The multimetal salt of a polyvalent inorganic acid refers to a salt obtained by an acid-base neutralization reaction between a base compound containing a metal component and a polyvalent inorganic acid, and particularly refers to a final salt compound containing two or more metal components. In other words, if the number of metal components in the chemical formula of a metal salt of a polyvalent inorganic acid is two or more, it is defined as a multimetal salt of a polyvalent inorganic acid.

[0046] The multi-metal salt of the polyvalent inorganic acid may include a di-metal salt of the polyvalent inorganic acid, a tri-metal salt of the polyvalent inorganic acid, a tetra-metal salt of the polyvalent inorganic acid, or a penta-metal salt of the polyvalent inorganic acid, depending on the number of metal components.

[0047] Examples of dimetal salts of polyvalent inorganic acids among the multimetal salts of polyvalent inorganic acids include sodium sulfate (Na2SO4), disodium hydrogen phosphate (Na2HPO4), and trisodium phosphate (Na3PO4).

[0048] The multimetal salt of a polyvalent inorganic acid acts as a co-catalyst during the synthesis of a polyester polymer, thereby shortening the polymerization time of the polyester polymer.

[0049] The monometallic salt of a polyvalent inorganic acid refers to a salt obtained by an acid-base neutralization reaction between a base compound containing a metal component and a polyvalent inorganic acid, and particularly refers to a final salt compound containing one (mono) metal component. In other words, if the chemical formula of a metal salt of a polyvalent inorganic acid contains one metal component, it is defined as a monometallic salt of a polyvalent inorganic acid. Examples of monometallic salts of polyvalent inorganic acids include sodium bisulfate (NaHSO4) and sodium dihydrogen phosphate (NaH2PO4).

[0050] The monometallic salt of a polyvalent inorganic acid acts as a co-catalyst during the synthesis of a polyester polymer, helping to shorten the polymerization time of the polyester polymer by the multimetallic salt of a polyvalent inorganic acid. Therefore, even a smaller amount of the multimetallic salt of a polyvalent inorganic acid can sufficiently shorten the polymerization time, thereby improving process efficiency.

[0051] Therefore, when a mixture of a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid is used, a sufficient reduction in polymerization time can be achieved with a smaller amount of the multimetallic salt of a polyvalent inorganic acid than with the monometallic salt of a polyvalent inorganic acid. In contrast, when only one monometallic salt of a polyvalent inorganic acid is used, the polymerization time of the polyester polymer increases to over 140 minutes, resulting in an insufficient reduction in polymerization time. When only one multimetallic salt of a polyvalent inorganic acid is used, an excess of the multimetallic salt of a polyvalent inorganic acid must be added to achieve a sufficient reduction in polymerization time, resulting in a problem of difficulty in ensuring process efficiency.

[0052] Specifically, the weight ratio of the multi-metal salt of a polyvalent inorganic acid to 1 part by weight of the mono-metal salt of a polyvalent inorganic acid may be 10 parts by weight or more, or 20 parts by weight or more, or 1000 parts by weight or less, or 500 parts by weight or less, or 100 parts by weight or less, or 50 parts by weight or less, or 10 parts by weight to 1000 parts by weight, or 20 parts by weight to 1000 parts by weight, or 10 parts by weight to 500 parts by weight, or 20 parts by weight to 500 parts by weight, or 10 parts by weight to 100 parts by weight, or 20 parts by weight to 100 parts by weight, or 10 parts by weight to 50 parts by weight, or 20 parts by weight to 50 parts by weight, or 20 parts by weight to 30 parts by weight, or 10 parts by weight to 20 parts by weight, or 10 parts by weight to 15 parts by weight.

[0053] If the weight ratio of the polyvalent inorganic acid multimetal salt to 1 part by weight of the polyvalent inorganic acid monometal salt is too low (less than 10 parts by weight), the effect of shortening the polymerization time of the polyester polymer by the polyvalent inorganic acid multimetal salt is difficult to fully achieve.If the weight ratio of the polyvalent inorganic acid multimetal salt to 1 part by weight of the polyvalent inorganic acid monometal salt is too high (more than 1000 parts by weight), an excessive amount of the polyvalent inorganic acid multimetal salt must be added, which makes it difficult to ensure process efficiency.

[0054] More specifically, the multimetal salt of a polyvalent inorganic acid is present in an amount of 10 ppm to 10,000 ppm, or 10 ppm to 5,000 ppm, or 10 ppm to 4,000 ppm, or 10 ppm to 2,000 ppm, or 10 ppm to 1,500 ppm, or 100 ppm to 10,000 ppm, or 100 ppm to 5,000 ppm, or 100 ppm to 4,000 ppm, or 100 ppm to 2,000 ppm, or 100 ppm It is contained at a content of up to 1500 ppm, or 500 ppm to 10000 ppm, or 500 ppm to 5000 ppm, or 500 ppm to 4000 ppm, or 500 ppm to 2000 ppm, or 500 ppm to 1500 ppm, or 1000 ppm to 10000 ppm, or 1000 ppm to 5000 ppm, or 1000 ppm to 4000 ppm, or 1000 ppm to 2000 ppm, or 1000 ppm to 1500 ppm.

[0055] The monometal salt of a polyvalent inorganic acid is contained in an amount of 0.1 ppm to 150 ppm, or 1 ppm to 150 ppm, or 10 ppm to 150 ppm, or 50 ppm to 150 ppm, or 100 ppm to 150 ppm, or 0.1 ppm to 100 ppm, or 1 ppm to 100 ppm, or 10 ppm to 100 ppm, or 50 ppm to 100 ppm, based on the weight of the polyester polymer.

[0056] The polyvalent inorganic acid is a polyprotic acid that releases more than one hydrogen ion among inorganic acids, and depending on the number of hydrogen ions, can include divalent inorganic acids, trivalent inorganic acids, tetravalent inorganic acids, pentavalent inorganic acids, etc. More specifically, examples of the polyvalent inorganic acid include sulfuric acid and phosphoric acid.

[0057] The metal may include an alkali metal or an alkaline earth metal, and specific examples of the metal include sodium, potassium, calcium, magnesium, or a mixture thereof.

[0058] The polyester polymer may have a yellowness index (YI) measured using a color meter of 24 or less, or 20 or less, or 15 or less, or 10 or less, or 1 or more, or 1 to 24, or 1 to 20, or 1 to 15, or 1 to 10. If the yellowness index of the polyester polymer measured using a color meter is excessively increased to exceed 24, there is a problem that it is difficult to ensure a high level of transparency due to excessive yellowing.

[0059] The polyester polymer has a melting point (T m) may be 150°C or higher, or 200°C or higher, or 210°C or higher, or 220°C or higher, or 223°C or higher, or 250°C or lower, or 240°C or lower, or 150°C to 250°C, or 200°C to 250°C, or 210°C to 250°C, or 220°C to 250°C, or 223°C to 250°C, or 150°C to 240°C, or 200°C to 240°C, or 210°C to 240°C, or 220°C to 240°C, or 223°C to 240°C. An example of a differential scanning calorimeter for measuring the melting point is a Differential Scanning Calorimetry (apparatus name: DSC2920, manufacturer: TA instrument) apparatus. The melting point can be determined from a temperature-heat flow graph obtained by scanning at a temperature range of 0°C to 250°C at a heating rate of 5°C / min to 15°C / min. More specifically, the melting point (T m ) was obtained by peak analysis of the heat flow heating curve during the second heating phase.

[0060] The polyester polymer has a melting point (T m If the temperature is too low below 150°C, the efficiency of the molding process for the polyester polymer may decrease.

[0061] The polyester polymer may have a crystallization temperature measured by a differential scanning calorimeter of 70°C or higher, or 150°C or higher, or 160°C or higher, or 170°C or higher, or 180°C or higher, or 183°C or higher, or 184°C or higher, or 200°C or lower, or 190°C or lower, or 70°C to 200°C, or 150°C to 200°C, or 160°C to 200°C, or 170°C to 200°C, or 180°C to 200°C, or 183°C to 200°C, or 184°C to 200°C, or 70°C to 190°C, or 150°C to 190°C, or 160°C to 190°C, or 170°C to 190°C, or 180°C to 190°C, or 183°C to 190°C, or 184°C to 190°C. An example of a differential scanning calorimeter for measuring the crystallization temperature is a Differential Scanning Calorimetry (device name: DSC2920, manufacturer: TA instrument). The crystallization temperature can be determined from a temperature-heat flow graph obtained by scanning at a heating rate of 5°C / min to 15°C / min in a temperature range of 0°C to 250°C or at a cooling rate of 5°C / min to 15°C / min. More specifically, the crystallization temperature (T c ) is determined by peak analysis of the cooling curve of the heat flow during the first cooling.

[0062] If the crystallization temperature of the polyester polymer measured by a differential scanning calorimeter is too low, below 70° C., the efficiency of the molding process for the polyester polymer may decrease.

[0063] The polyester polymer may have an intrinsic viscosity, as measured by DIN-53728-3, of 0.5 dL / g or more, or 0.6 dL / g or more, or 0.7 dL / g or more, or 0.8 dL / g or more, or 0.9 dL / g or more, or 0.95 dL / g or more, or 0.96 dL / g or more, or 0.97 dL / g or more, and an upper limit of 10 dL / g or less, or 5 dL / g or less, or 1 dL / g or less, or 0.98 dL / g or less. The upper and lower limit ranges may be combined to satisfy a numerical range between the lower and upper limits. For example, the intrinsic viscosity, as measured by DIN-53728-3, may be 0.5 dL / g to 10 dL / g.

[0064] The polyester polymer is not particularly limited in its application, and can be used in any of the application fields of conventionally known thermoplastic polyester polymers, including, for example, automobile parts, automobile interior materials, automobile exterior materials, cables, wires, hoses, tubes, antenna covers, leisure goods, and sporting goods.

[0065] There is no limitation on the molding process for such applications, and various conventionally known molding processes for thermoplastic polyester polymers can be applied without limitation.

[0066] 2. Method for producing polyester polymer According to another embodiment of the present invention, there is provided a method for producing a polyester polymer, comprising: a) an esterification reaction step of reacting a diol and a dicarboxylic acid or a derivative thereof in the presence of a catalyst and a co-catalyst; b) a first condensation polymerization step of adding a catalyst to the reaction mixture obtained after the completion of step a) and carrying out condensation polymerization under reduced pressure to produce a prepolymer; and c) a second condensation polymerization step of condensing the prepolymer under a pressure condition lower than that of step b), wherein the co-catalyst comprises a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid.

[0067] Specifically, the method for producing the polyester polymer may include a) an esterification step of reacting a diol and a dicarboxylic acid or a derivative thereof in the presence of a catalyst and a cocatalyst.

[0068] In the present invention, the diol is preferably an aliphatic or alicyclic diol having 2 to 10 carbon atoms and a molecular weight of 300 g / mol or less, in terms of achieving the effects of the present invention. Specific examples of diols that can be used in the present invention include, but are not limited to, aliphatic diols such as 1,4-butylene glycol (1,4-butanediol), monoethylene glycol, diethylene glycol, propylene glycol, and neopentyl glycol; and alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and tricyclodecanedimethanol. Specifically, in the present invention, the diol may be 1,4-butanediol, an aliphatic diol.

[0069] Examples of dicarboxylic acids that can be used in the present invention include, but are not limited to, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, and sebacic acid. Specifically, the dicarboxylic acid may be terephthalic acid.

[0070] Examples of dicarboxylic acid derivatives that can be used in the present invention include, but are not limited to, dialkyl terephthalate, dialkyl isophthalate, dialkyl naphthalenedicarboxylate, dialkyl adipate, and dialkyl sebacate. Specifically, the dicarboxylic acid or its derivative may be dimethyl terephthalate, which is a derivative of an aromatic dicarboxylic acid.

[0071] The esterification reaction of the diol and dicarboxylic acid or its derivative is carried out in the presence of a catalyst (main catalyst) and a co-catalyst. The catalyst (main catalyst) can be any suitable catalyst known in the art. Specifically, the catalyst (main catalyst) can be a catalyst containing titanium or tin as an active metal. More specifically, the catalyst can be a titanium-based catalyst such as tetrabutyl titanate (TBT), tetraethyl titanate, or tetra(isopropyl)titanate; or a tin-based catalyst such as n-butylstannoic acid, octylstannoic acid, dimethyltin oxide, dibutyltin oxide, dioctyltin oxide, diphenyltin oxide, tri-n-butyltin acetate, tri-n-butyltin chloride, or tri-n-butyltin fluoride. In addition to the above catalysts, oxides or acetates containing Mg, Ca, Mn, Zn, Pb, Zr, etc. as active metals can also be used alone or in combination. Of these, titanium-based catalysts such as TBT are preferably used.

[0072] Meanwhile, in the present invention, the catalyst is added not only in the esterification reaction but also in the polycondensation step. Generally, in the production of a polyester polymer, the catalyst for the esterification (or transesterification) reaction and the polycondensation reaction is the same, and no separation step is required between the two reactions. Therefore, after adding a certain amount of catalyst at the start of or during the initial esterification (or transesterification) reaction, it is not necessary to add additional catalyst in the polycondensation step.

[0073] The co-catalyst can include a monometal salt of a polyvalent inorganic acid and a dimetal salt of a polyvalent inorganic acid. The multimetal salt of a polyvalent inorganic acid refers to a salt obtained by an acid-base neutralization reaction between a base compound containing a metal component and a polyvalent inorganic acid, and particularly refers to a final salt compound containing two or more metal components. In other words, if the number of metal components in the chemical formula of a metal salt of a polyvalent inorganic acid is two or more, it is defined as a multimetal salt of a polyvalent inorganic acid.

[0074] The multi-metal salt of the polyvalent inorganic acid may include a di-metal salt of the polyvalent inorganic acid, a tri-metal salt of the polyvalent inorganic acid, a tetra-metal salt of the polyvalent inorganic acid, or a penta-metal salt of the polyvalent inorganic acid, depending on the number of metal components.

[0075] Examples of dimetal salts of polyvalent inorganic acids among the multimetal salts of polyvalent inorganic acids include sodium sulfate (Na2SO4), disodium hydrogen phosphate (Na2HPO4), and trisodium phosphate (Na3PO4).

[0076] The multimetal salt of a polyvalent inorganic acid acts as a co-catalyst during the synthesis of a polyester polymer, thereby shortening the polymerization time of the polyester polymer.

[0077] The monometallic salt of a polyvalent inorganic acid refers to a salt obtained by an acid-base neutralization reaction between a base compound containing a metal component and a polyvalent inorganic acid, and particularly refers to a final salt compound containing one (mono) metal component. In other words, if the chemical formula of a metal salt of a polyvalent inorganic acid contains one metal component, it is defined as a monometallic salt of a polyvalent inorganic acid. Examples of monometallic salts of polyvalent inorganic acids include sodium bisulfate (NaHSO4) and sodium dihydrogen phosphate (NaH2PO4).

[0078] The monometallic salt of a polyvalent inorganic acid acts as a co-catalyst during the synthesis of a polyester polymer, helping to shorten the polymerization time of the polyester polymer by the multimetallic salt of a polyvalent inorganic acid. Therefore, even a smaller amount of the multimetallic salt of a polyvalent inorganic acid can sufficiently shorten the polymerization time, thereby improving process efficiency.

[0079] Therefore, when a mixture of a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid is used, a sufficient reduction in polymerization time can be achieved with a smaller amount of the multimetallic salt of a polyvalent inorganic acid than with the monometallic salt of a polyvalent inorganic acid. In contrast, when only one monometallic salt of a polyvalent inorganic acid is used, the polymerization time of the polyester polymer increases to over 140 minutes, resulting in an insufficient reduction in polymerization time. When only one multimetallic salt of a polyvalent inorganic acid is used, an excess of the multimetallic salt of a polyvalent inorganic acid must be added to achieve a sufficient reduction in polymerization time, resulting in a problem of difficulty in ensuring process efficiency.

[0080] Specifically, the weight ratio of the multi-metal salt of a polyvalent inorganic acid to 1 part by weight of the mono-metal salt of a polyvalent inorganic acid may be 10 parts by weight or more, or 20 parts by weight or more, or 1000 parts by weight or less, or 500 parts by weight or less, or 100 parts by weight or less, or 50 parts by weight or less, or 10 parts by weight to 1000 parts by weight, or 20 parts by weight to 1000 parts by weight, or 10 parts by weight to 500 parts by weight, or 20 parts by weight to 500 parts by weight, or 10 parts by weight to 100 parts by weight, or 20 parts by weight to 100 parts by weight, or 10 parts by weight to 50 parts by weight, or 20 parts by weight to 50 parts by weight, or 20 parts by weight to 30 parts by weight, or 10 parts by weight to 20 parts by weight, or 10 parts by weight to 15 parts by weight.

[0081] If the weight ratio of the polyvalent inorganic acid multimetal salt to 1 part by weight of the polyvalent inorganic acid monometal salt is too low (less than 10 parts by weight), the effect of shortening the polymerization time of the polyester polymer by the polyvalent inorganic acid multimetal salt is difficult to fully achieve.If the weight ratio of the polyvalent inorganic acid multimetal salt to 1 part by weight of the polyvalent inorganic acid monometal salt is too high (more than 1000 parts by weight), an excessive amount of the polyvalent inorganic acid multimetal salt must be added, which makes it difficult to ensure process efficiency.

[0082] More specifically, the multimetal salt of the polyvalent inorganic acid is present in an amount of 10 ppm to 10,000 ppm, or 10 ppm to 5,000 ppm, or 10 ppm to 4,000 ppm, or 10 ppm to 2,000 ppm, or 10 ppm to 1,500 ppm, or 100 ppm to 10,000 ppm, or 100 ppm to 5,000 ppm, or 100 ppm to 4,000 ppm, or 100 ppm to 2,000 ppm, or 100 ppm to 2,000 ppm, based on the weight of the reaction mixture after step a) is completed. It is contained at a content of ppm to 1500 ppm, or 500 ppm to 10000 ppm, or 500 ppm to 5000 ppm, or 500 ppm to 4000 ppm, or 500 ppm to 2000 ppm, or 500 ppm to 1500 ppm, or 1000 ppm to 10000 ppm, or 1000 ppm to 5000 ppm, or 1000 ppm to 4000 ppm, or 1000 ppm to 2000 ppm, or 1000 ppm to 1500 ppm.

[0083] In addition, the monometal salt of a polyvalent inorganic acid may be present in an amount of 0.1 ppm to 150 ppm, or 1 ppm to 150 ppm, or 10 ppm to 150 ppm, or 50 ppm to 150 ppm, or 100 ppm to 150 ppm, or 0.1 ppm to 100 ppm, or 1 ppm to 100 ppm, or 10 ppm to 100 ppm, or 50 ppm to 100 ppm, based on the weight of the reaction mixture after step a) is completed.

[0084] The polyvalent inorganic acid is a polyprotic acid that releases more than one hydrogen ion among inorganic acids, and depending on the number of hydrogen ions, can include divalent inorganic acids, trivalent inorganic acids, tetravalent inorganic acids, pentavalent inorganic acids, etc. More specifically, examples of the polyvalent inorganic acid include sulfuric acid and phosphoric acid.

[0085] The metal may include an alkali metal or an alkaline earth metal, and specific examples of the metal include sodium, potassium, calcium, magnesium, or a mixture thereof.

[0086] Meanwhile, in the present invention, a certain amount of the co-catalyst may be added at the start of the initial esterification (or transesterification) reaction, at the initial stage of the reaction, or at the final stage of the reaction, and may also be added additionally in the polycondensation step, if necessary.

[0087] The reaction temperature in step a) is suitably in the range of 150°C to 300°C or 200°C to 240°C, and the reaction pressure may be in the range of 100 torr to 760 torr. Specifically, after the starting materials and the catalyst are charged into a reactor, the temperature is increased at a rate of 0.1°C / min to 10°C / min with stirring until the temperature reaches the above range, and the esterification reaction can be carried out for about 30 minutes to 4 hours, or 1 to 2 hours.

[0088] After step a) is completed, the polycondensation steps b) and c) are then carried out. The polycondensation step is carried out in a reactor separate from the esterification reactor and without a distillation column. Specifically, the polycondensation step is carried out after adding an additional catalyst of 50 ppm or more based on active metal to the reaction mixture after step a).

[0089] In the present invention, the polycondensation step is divided into two steps, b) and c). Steps b) and c) are carried out substantially continuously, but differ in pressure conditions. Specifically, step b) is a process for removing excess diol, and step c) is a process for increasing the viscosity of the polyester polymer.

[0090] Specifically, the method for preparing the polyester polymer may include b) a first condensation polymerization step of adding a catalyst to the reaction mixture obtained after step a) and condensing the mixture under reduced pressure to prepare a prepolymer.

[0091] Step b) of the present invention is a first polycondensation step carried out under relatively mild conditions, in which a catalyst is additionally added to the reaction mixture after step a), and the mixture is stirred under reduced pressure to carry out polycondensation to obtain a prepolymer.

[0092] Step b) is carried out at a temperature of 180°C to 250°C and a pressure of 5 to 100 torr. Under these conditions, the excess diol that has not reacted in step a) is vaporized and removed. The reaction time for step b) is not particularly limited, but may be 20 minutes to 1 hour, or 20 minutes to 40 minutes.

[0093] If polycondensation is carried out immediately under a high vacuum of 5 torr or less without carrying out step b), the unreacted diol may be rapidly vaporized, causing bumping in the reactor and a rapid drop in the temperature of the reactants. Furthermore, this may result in a problem that a polyester polymer with high viscosity cannot be obtained. Therefore, in the present invention, a preliminary first polycondensation step is carried out under relaxed conditions before the full polycondensation reaction.

[0094] Meanwhile, in step a) or b), one or more commonly used additives may be added together to improve the reaction efficiency and adjust the physical properties of the polyester polymer produced.

[0095] Examples of additives that can be used include, but are not limited to, branching agents (e.g., glycerol, sorbitol, pentaerythritol, 1,1,4,4-tetrakis(hydroxymethyl)cyclohexane, trimethylolpropane, pyromellitic acid, 1,1,2,2-ethanetetracarboxylic acid, etc.) for increasing the melt strength of the polyester polymer, matting agents (e.g., TiO, zinc sulfide, or zinc oxide) for improving color properties, colorants (e.g., dyes), stabilizers (e.g., antioxidants, ultraviolet light stabilizers, heat stabilizers, etc.), fillers, flame retardants, pigments, antimicrobial agents, antistatic agents, optical brighteners, extenders, processing aids, or viscosity enhancers, any one or mixtures of two or more of these. As an example, a stabilizer in the form of hindered phenol (e.g., Irganox 1330) can be incorporated to enhance the thermal stability of the polyester polymer.

[0096] These additives can be used in an appropriate amount within a range that ensures the intended effect and does not deteriorate the physical properties of the polyester polymer produced; specifically, they can be used in an amount of 0.1 to 10% by weight based on 100% by weight of the total raw materials.

[0097] The method for preparing the polyester polymer may also include a second polycondensation step of polycondensing the prepolymer under a pressure condition lower than that of step c) or b).

[0098] Step c) is a reaction subsequent to step b), in which the prepolymer is polycondensed in the same reactor only at a further reduced pressure.

[0099] In step c), the time from the start of the reaction to the point at which the torque value attached to the mechanical stirrer reaches 0.8 Nm and the reaction is terminated may be 95 minutes or less, or 91 minutes or less, or 90 minutes or less, or 80 minutes or less, or 70 minutes or less, or 50 minutes or more, or 50 to 95 minutes, or 50 to 90 minutes, or 50 to 80 minutes, or 50 to 70 minutes. If the time from the start of the reaction to the point at which the torque value attached to the mechanical stirrer reaches 0.8 Nm and the reaction is terminated is excessively long, the polymerization time may not be sufficiently shortened, resulting in a problem of reduced productivity.

[0100] Step c) is carried out at a temperature of 180°C to 250°C and a pressure of 5 torr or less. Under these conditions, the polycondensation is carried out for about 30 minutes to 5 hours, or 1 to 3 hours, and the reaction is completed when the torque value reaches a range of 0.5 Nm to 2.0 Nm, finally producing a polyester polymer.

[0101] 3. Catalyst System According to yet another embodiment of the invention, there is provided a catalyst system comprising a catalyst and a co-catalyst, wherein the co-catalyst comprises a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid.

[0102] The catalyst system can be used to synthesize a variety of polymers, and specific examples of the polymers are not particularly limited, and can be used without limitation to conventionally known polymers. However, examples include polyester (co)polymers, polyetherester copolymers, polyolefin (co)polymers, polycarbonate (co)polymers, polyurethane (co)polymers, polyamide (co)polymers, polyimide (co)polymers, polysulfone (co)polymers, polyacetal (co)polymers, polyketone (co)polymers, and polyacrylic (co)polymers. The term "co)polymer" includes both homopolymers and copolymers.

[0103] The catalyst (main catalyst) may be any material known in the art. Specifically, the catalyst (main catalyst) may contain titanium or tin as an active metal. More specifically, the catalyst may be a titanium-based catalyst such as tetrabutyl titanate (TBT), tetraethyl titanate, or tetra(isopropyl)titanate; or a tin-based catalyst such as n-butylstannic acid, octylstannic acid, dimethyltin oxide, dibutyltin oxide, dioctyltin oxide, diphenyltin oxide, tri-n-butyltin acetate, tri-n-butyltin chloride, or tri-n-butyltin fluoride. In addition to the above catalysts, catalysts such as oxides or acetates containing Mg, Ca, Mn, Zn, Pb, Zr, etc. as active metals may be used alone or in combination. Among these, titanium-based catalysts such as TBT are preferred.

[0104] The co-catalyst can include a monometal salt of a polyvalent inorganic acid and a dimetal salt of a polyvalent inorganic acid. The multimetal salt of a polyvalent inorganic acid refers to a salt obtained by an acid-base neutralization reaction between a base compound containing a metal component and a polyvalent inorganic acid, and particularly refers to a final salt compound containing two or more metal components. In other words, if the number of metal components in the chemical formula of a metal salt of a polyvalent inorganic acid is two or more, it is defined as a multimetal salt of a polyvalent inorganic acid.

[0105] The multi-metal salt of the polyvalent inorganic acid may include a di-metal salt of the polyvalent inorganic acid, a tri-metal salt of the polyvalent inorganic acid, a tetra-metal salt of the polyvalent inorganic acid, or a penta-metal salt of the polyvalent inorganic acid, depending on the number of metal components.

[0106] Examples of dimetal salts of polyvalent inorganic acids among the multimetal salts of polyvalent inorganic acids include sodium sulfate (Na2SO4), disodium hydrogen phosphate (Na2HPO4), and trisodium phosphate (Na3PO4).

[0107] The multimetal salt of a polyvalent inorganic acid acts as a co-catalyst and can shorten the polymerization time.

[0108] The monometallic salt of a polyvalent inorganic acid refers to a salt obtained by an acid-base neutralization reaction between a base compound containing a metal component and a polyvalent inorganic acid, and particularly refers to a final salt compound containing one (mono) metal component. In other words, if the chemical formula of a metal salt of a polyvalent inorganic acid contains one metal component, it is defined as a monometallic salt of a polyvalent inorganic acid. Examples of monometallic salts of polyvalent inorganic acids include sodium bisulfate (NaHSO4) and sodium dihydrogenphosphate (NaH2PO4).

[0109] The monometallic salt of a polyvalent inorganic acid acts as a promoter to assist in shortening the polymerization time by the multimetallic salt of a polyvalent inorganic acid. This allows the polymerization time to be sufficiently shortened even with a smaller amount of the multimetallic salt of a polyvalent inorganic acid, thereby improving process efficiency.

[0110] Therefore, when a mixture of a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid is used, a sufficient polymerization time reduction effect can be achieved with a smaller amount of the multimetallic salt of a polyvalent inorganic acid than with the monometallic salt of a polyvalent inorganic acid. In contrast, when only one monometallic salt of a polyvalent inorganic acid is used, the polymerization time is not sufficiently reduced, and when only one multimetallic salt of a polyvalent inorganic acid is used, an excess of the multimetallic salt of a polyvalent inorganic acid must be added to achieve a sufficient level of polymerization time reduction, which makes it difficult to ensure process efficiency.

[0111] Specifically, the weight ratio of the multi-metal salt of a polyvalent inorganic acid to 1 part by weight of the mono-metal salt of a polyvalent inorganic acid may be 10 parts by weight or more, or 20 parts by weight or more, or 1000 parts by weight or less, or 500 parts by weight or less, or 100 parts by weight or less, or 50 parts by weight or less, or 10 parts by weight to 1000 parts by weight, or 20 parts by weight to 1000 parts by weight, or 10 parts by weight to 500 parts by weight, or 20 parts by weight to 500 parts by weight, or 10 parts by weight to 100 parts by weight, or 20 parts by weight to 100 parts by weight, or 10 parts by weight to 50 parts by weight, or 20 parts by weight to 50 parts by weight, or 20 parts by weight to 30 parts by weight, or 10 parts by weight to 20 parts by weight, or 10 parts by weight to 15 parts by weight.

[0112] If the weight ratio of the polyvalent inorganic acid multimetal salt to 1 part by weight of the polyvalent inorganic acid monometal salt is too low, such as less than 10 parts by weight, the effect of shortening the polymerization time due to the polyvalent inorganic acid multimetal salt is difficult to fully achieve.If the weight ratio of the polyvalent inorganic acid multimetal salt to 1 part by weight of the polyvalent inorganic acid monometal salt is too high, such as more than 1000 parts by weight, an excessive amount of the polyvalent inorganic acid multimetal salt must be added, which makes it difficult to ensure process efficiency.

[0113] More specifically, the multimetal salt of the polyvalent inorganic acid is present in an amount of 10 ppm to 10,000 ppm, or 10 ppm to 5,000 ppm, or 10 ppm to 4,000 ppm, or 10 ppm to 2,000 ppm, or 10 ppm to 1,500 ppm, or 100 ppm to 10,000 ppm, or 100 ppm to 5,000 ppm, or 100 ppm to 4,000 ppm, or 100 ppm to 2,000 ppm, or 100 ppm to 2,000 ppm, based on the weight of the reaction mixture after step a) is completed. It is contained at a content of ppm to 1500 ppm, or 500 ppm to 10000 ppm, or 500 ppm to 5000 ppm, or 500 ppm to 4000 ppm, or 500 ppm to 2000 ppm, or 500 ppm to 1500 ppm, or 1000 ppm to 10000 ppm, or 1000 ppm to 5000 ppm, or 1000 ppm to 4000 ppm, or 1000 ppm to 2000 ppm, or 1000 ppm to 1500 ppm.

[0114] In addition, the monometal salt of a polyvalent inorganic acid may be present in an amount of 0.1 ppm to 150 ppm, or 1 ppm to 150 ppm, or 10 ppm to 150 ppm, or 50 ppm to 150 ppm, or 100 ppm to 150 ppm, or 0.1 ppm to 100 ppm, or 1 ppm to 100 ppm, or 10 ppm to 100 ppm, or 50 ppm to 100 ppm, based on the weight of the reaction mixture after step a) is completed.

[0115] The polyvalent inorganic acid is a polyprotic acid that releases more than one hydrogen ion among inorganic acids, and depending on the number of hydrogen ions, can include divalent inorganic acids, trivalent inorganic acids, tetravalent inorganic acids, pentavalent inorganic acids, etc. More specifically, examples of the polyvalent inorganic acid include sulfuric acid and phosphoric acid.

[0116] The metal may include an alkali metal or an alkaline earth metal, and specific examples of the metal include sodium, potassium, calcium, magnesium, or a mixture thereof. [Effects of the Invention]

[0117] According to the present invention, it is possible to provide a polyester polymer, a production method thereof, and a catalyst system that can significantly reduce the polymerization time and increase productivity while maintaining excellent physical properties. DETAILED DESCRIPTION OF THE INVENTION

[0118] The present invention will be described in more detail in the following examples, but the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0119] <Examples and Comparative Examples: Production of Polyester Polymer> Example 1 A 2L glass reactor was charged with 120g of terephthalic acid, 200g of 1,4-butanediol, 50ppm (Ti element basis) of tetrabutyl titanate (TBT) catalyst, 1,200ppm (based on the total amount of raw materials) of sodium sulfate (Na2SO4) and 50ppm (based on the total amount of raw materials) of sodium bisulfate (NaHSO4) as co-catalysts, and the mixture was stirred under nitrogen for 2 hours at 230°C. The temperature was then increased and the esterification (ES) reaction was carried out at a pressure of 100-760 torr.

[0120] After the ES reaction, 50 ppm (Ti element basis) of tetrabutyl titanate (TBT) catalyst was added to the reactor and stirred for 10 minutes. After removing the liquid by-product generated in the Dean-Stark trap, the pressure was reduced to 10 torr at 230-240°C for 30 minutes, and the first polycondensation (PP) reaction was carried out.

[0121] The second polycondensation (PC) reaction was then carried out at 240-250°C and 1 torr or less. During the PC reaction, the torque attached to the mechanical stirrer continuously increased, and when the torque reached 0.8 Nm, the reaction was stopped, and the product was cooled by discharging it into cold water under pressure and then dried to obtain polybutylene terephthalate (PBT) polymer.

[0122] (Example 2, Comparative Examples 1 to 3) As shown in Table 1 below, PBT was obtained in the same manner as in Example 1, except that the content or type of the promoters, sodium sulfate (NaSO) and sodium bisulfate (NaHSO), was changed.

[0123] <Experimental example: Measurement of physical properties of polyester polymer> The physical properties of the polyester polymers obtained in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1.

[0124] 1. Secondary Polycondensation (PC) Reaction Time (unit: minutes) In the examples and comparative examples, the time from the start of the second polycondensation (PC) reaction to the point at which the torque value attached to the mechanical stirrer reached 0.8 Nm and the reaction was stopped was measured.

[0125] 2. Intrinsic viscosity (unit: dL / g) The intrinsic viscosity was measured in the same manner as in DIN-53728-3 by drying the polyester polymers obtained in the examples and comparative examples in an oven at 80°C for at least 2 hours, dissolving the resulting sample in a mixed solvent of o-cresol and 1,2-dichlorobenzene (1:1 by weight), and then measuring the intrinsic viscosity at 25°C using an Ubbelohde viscometer.

[0126] 3. Melting point, crystallization temperature (unit: °C) The polyester polymers obtained in the examples and comparative examples were scanned twice using a differential scanning calorimeter (DSC2920, manufactured by TA Instrument) in a temperature range of 0°C to 250°C at a heating rate or cooling rate of 10°C / min, and the melting point (T m ) and crystallization temperature (T c ) was measured. The crystallization temperature (T c ) is obtained by peak analysis of the heat flow cooling curve during the first cooling phase, and the melting point (T m ) was obtained by peak analysis of the heat flow heating curve during the second heating phase.

[0127] 4.Yellow index The polyester polymers obtained in the above examples and comparative examples were measured using a color meter ZE6000 (NIPPON DENSHOKU).

[0128] [Table 1]

[0129] As shown in Table 1, the polyester polymers of Examples 1 and 2 exhibited physical properties such as intrinsic viscosity, melting point, crystallization temperature, and yellowness index at the same levels as those of the Comparative Examples and Reference Examples, but the PC reaction time was shortened to 70 minutes or 91 minutes, which is shorter than the PC reaction times of the Comparative Examples, which had PC reaction times of 97 minutes, 112 minutes, and 120 minutes, thereby improving process efficiency.

Claims

1. a polymeric matrix comprising polyester repeat units; and monometallic salts of polyvalent inorganic acids and multimetallic salts of polyvalent inorganic acids that remain in the polymer matrix; the multimetal salt of a polyvalent inorganic acid is sodium sulfate; The polyester polymer, wherein the monometallic salt of a polyvalent inorganic acid is sodium hydrogen sulfate.

2. 2. The polyester polymer of claim 1, wherein the polyester polymer has a yellowness index of 24 or less as measured using a color meter.

3. 2. The polyester polymer according to claim 1, wherein the polyester polymer has a melting point of 150°C or higher as measured by a differential scanning calorimeter.

4. 2. The polyester polymer according to claim 1, wherein the polyester polymer has a crystallization temperature of 70°C or higher as measured by a differential scanning calorimeter.

5. 2. The polyester polymer according to claim 1, wherein the weight ratio of the multimetal salt of a polyvalent inorganic acid to 1 part by weight of the monometal salt of a polyvalent inorganic acid is 10 parts by weight or more.

6. 2. The polyester polymer according to claim 1, wherein the multimetal salt of a polyvalent inorganic acid is contained in an amount of 10 ppm to 10,000 ppm based on the weight of the polyester polymer.

7. 2. The polyester polymer according to claim 1, wherein the monometallic salt of a polyvalent inorganic acid is contained in an amount of 0.1 ppm to 150 ppm based on the weight of the polyester polymer.

8. 2. The polyester polymer of claim 1, wherein the polyester repeating unit has a structure represented by the following Chemical Formula 1: 【Chemical 1】 In the above Chemical Formula 1, R 1 is one of an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 3 to 10 carbon atoms, or an arylene group having 6 to 20 carbon atoms, R 2 is an alkylene group having 1 to 10 carbon atoms.

9. The polyester polymer of claim 1 , wherein the polymer matrix comprises at least one type of polyester repeat unit.

10. a) an esterification step in which a diol and a dicarboxylic acid or a derivative thereof are reacted in the presence of a catalyst and a co-catalyst; b) a first polycondensation step in which a catalyst is added to the reaction mixture obtained after the step a) and polycondensed under reduced pressure to prepare a prepolymer; and c) a second polycondensation step in which the prepolymer is polycondensed under a pressure condition lower than that in step b); the co-catalyst comprises a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid; The method for producing a polyester polymer, wherein the weight ratio of the multimetal salt of a polyvalent inorganic acid to 1 part by weight of the monometal salt of a polyvalent inorganic acid is 10 parts by weight or more.

11. 11. The method according to claim 10, wherein in step c), the time from the start of the reaction to the termination of the reaction when the torque value attached to a mechanical stirrer reaches 0.8 Nm is 95 minutes or less.

12. 11. The method for producing a polyester polymer according to claim 10, wherein the multimetal salt of a polyvalent inorganic acid is added in an amount of 10 ppm to 10,000 ppm based on the weight of the reaction mixture after step a).

13. The method for producing a polyester polymer according to claim 10, wherein the monometallic salt of a polyvalent inorganic acid is added in an amount of 0.1 ppm to 150 ppm based on the weight of the reaction mixture after step a) is completed.

14. the multimetal salt of a polyvalent inorganic acid is sodium sulfate; The method for producing a polyester polymer according to claim 10, wherein the monometallic salt of a polyvalent inorganic acid is sodium hydrogen sulfate.

15. a catalyst and a co-catalyst; the co-catalyst comprises a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid; the multimetal salt of a polyvalent inorganic acid is sodium sulfate; 1. A catalyst system for use in the production of polyester polymers, wherein the monometallic salt of a polyvalent inorganic acid is sodium hydrogen sulfate.

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