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 dated December 6, 2022 and Korean Patent Application No. 10-2023-0065848 dated 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 capable of significantly shortening polymerization time and increasing productivity while maintaining excellent physical properties, and to a production method and catalyst system thereof. [Background technology]

[0003] Polyester polymers are commercially produced by a two-stage reaction of esterification or ester exchange reaction of diols, dicarboxylic acids or dicarboxylates as raw materials, followed by polycondensation of the reaction product.

[0004] As an example, polybutylene terephthalate (PBT) polymer, which is one of the widely known polyester polymers, is produced through esterification and condensation polymerization steps using 1,4-butylene glycol (BG) and terephthalic acid (TPA) as starting materials.

[0005] Meanwhile, in the polycondensation step, in order to improve productivity, a co-catalyst can be additionally applied 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), 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 is still poor, making it unsuitable for mass production.

[0007] Therefore, there is a need for a method for producing polyester polymers that can produce polyester polymers having similar thermal and mechanical properties to conventional methods while shortening the polymerization time sufficiently to be 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 and increase productivity while maintaining excellent physical properties.

[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 the production of said polyester polymer. [Means for solving the problem]

[0011] In order to solve the above problems, the present specification provides a polyester polymer comprising: a polymer matrix including polyester repeat 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 producing a prepolymer by adding a catalyst to the reaction mixture after the completion of the step a) and carrying out condensation polymerization under reduced pressure; and c) a second condensation polymerization step of condensing the prepolymer under a pressure condition lower than that of the 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, said co-catalyst comprising: a mono-metal salt of a polyvalent inorganic acid; and a multi-metal 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, the terminology used is for the purpose of referring to particular embodiments only and is not intended to be limiting of the invention.

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

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

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

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

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

[0021] In the present specification, the term "substituted or unsubstituted" means that the group is substituted or unsubstituted with one or more substituents 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, alkylthio, arylthio, alkylsulfoxy, arylsulfoxy, silyl, boron, alkyl, cycloalkyl, alkenyl, aryl, aralkyl, aralkenyl, alkylaryl, alkoxysilylalkyl, arylphosphine, or heterocyclic groups containing one or more of N, O, and S atoms, or that the group is substituted or unsubstituted with two or more of the above-listed substituents. For example, the "substituent with two or more substituents connected" may be a biphenyl group. In other words, the biphenyl group may be an aryl group, and may be interpreted as a substituent with two phenyl groups connected.

[0022] In this specification, [ka] or [ka] means a bond that is connected to another substituent, and a direct bond means that there is no other atom present 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 that satisfies all of the following three conditions can be defined as aromatic. 1) There must be 4n+2 electrons present in complete conjugation through 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 something that does not satisfy the above-mentioned aromaticity.

[0025] In this specification, the alkyl group is a monovalent functional group derived from an alkane, which 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. Also, 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-methyl-butyl, 1-ethyl-butyl, 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-ethyl-propyl, 1,1-dimethyl-propyl, 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 substituents are as described above.

[0026] In the present specification, a cycloalkyl group is a monovalent functional group derived from a cycloalkane, which may be monocyclic or polycyclic, and 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, and if substituted, examples of the substituent are as described above.

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

[0028] In this specification, the 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, an ethylene group, a propylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, a pentylene group, a 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, the arylene group is a divalent functional group derived from arene, and the above description of the aryl group is applicable except that these are divalent functional groups. For example, it may be a phenylene group, a biphenylene group, a terphenylene group, a naphthalene group, a fluorenyl group, a pyrenyl group, a phenanthrenyl group, a perylene group, a tetracenyl group, an 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, oxidizing, reducing, substituting an atom, or the like, 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 including polyester repeat 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 a co-catalyst during synthesis of the polyester polymer, the production efficiency of the polyester polymer can be improved while maintaining excellent physical properties, and thus completed the invention.

[0035] The monometal salt of a polyvalent inorganic acid and the multimetal salt of a polyvalent inorganic acid can be added as a co-catalyst together with the monomeric diol, dicarboxylic acid or its derivative, and main catalyst in the synthesis process of the polyester polymer, and a part or the whole of the co-catalyst may remain in the final synthesized polyester polymer.

[0036] Specifically, the polyester polymer may include a polymer matrix containing a polyester repeating unit. 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 includes one type of polyester repeating unit, a polyester homopolymer may be formed, and when the polymer matrix includes two or more types of polyester repeating units, a polyester copolymer may be formed.

[0037] The polyester homopolymer is a polyester polymer synthesized by reacting one kind of diol with a dicarboxylic acid or one kind of derivative thereof, and the polyester copolymer may be a polyester polymer synthesized by reacting one kind of diol with two or more kinds of dicarboxylic acids or derivatives thereof, or a polyester polymer synthesized by reacting two or more kinds of diols with a dicarboxylic acid or one kind of derivative thereof, or a polyester polymer synthesized by reacting two or more kinds of diols with two or more kinds of 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. An example of the dicarboxylic acid or a derivative thereof is terephthalic acid, which is an aromatic dicarboxylic acid, and an example of the diol is 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 a diol monomer, a dicarboxylic acid or its derivative, and a main catalyst during the synthesis of the polyester polymer, and may remain in part or in whole 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 types of metal salt promoters of polyvalent inorganic acids remaining in the polyester polymer can be confirmed by quantitative analysis of metal elements (e.g., Na and S) using ICP. In addition, the content and ratio of two types of metal salt promoters of polyvalent inorganic acids can be confirmed by ion chromatography analysis or a combination of ICP and ion chromatography analysis.

[0045] The multi-metal salt of a polyvalent inorganic acid means 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 2(di) 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 2 or more, it is defined as a multi-metal salt of a polyvalent inorganic acid.

[0046] The multi-metal salt of the polyvalent inorganic acid may include a dimetal salt of a polyvalent inorganic acid, a trimetal salt of a polyvalent inorganic acid, a tetrametal salt of a polyvalent inorganic acid, or a pentametal salt of a polyvalent inorganic acid, depending on the number of metal components.

[0047] Among the multiple metal salts of polyvalent inorganic acids, examples of dimetal 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 means 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 number of metal components in the chemical formula of a metal salt of a polyvalent inorganic acid is one, it is defined as a monometallic salt of a polyvalent inorganic acid. Examples of the monometallic salt of a polyvalent inorganic acid include sodium bisulfate (NaHSO4) and sodium dihydrogen phosphate (NaH2PO4).

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

[0051] Therefore, when a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid are mixed, a sufficient polymerization time shortening effect can be achieved with a smaller amount of the multimetal salt of a polyvalent inorganic acid due to the monometal salt of the polyvalent inorganic acid. On the other hand, when only one monometal salt of a polyvalent inorganic acid is used, the polymerization time of the polyester polymer increases to more than 140 minutes, which is a problem in that the polymerization time is not shortened sufficiently, and when only one multimetal salt of a polyvalent inorganic acid is used, an excessive amount of the multimetal salt of a polyvalent inorganic acid must be added to shorten the polymerization time to a sufficient level, which is a problem in that the efficiency of the process is difficult to ensure.

[0052] Specifically, the weight ratio of the multiple metal salt of a polyvalent inorganic acid to 1 part by weight of the monometal 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 multiple metal 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 of the polyester polymer by the polyvalent inorganic acid multiple metal salt is difficult to fully achieve.If the weight ratio of the polyvalent inorganic acid multiple metal 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 multiple metal salt must be added, which makes it difficult to ensure the efficiency of the process.

[0054] 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 ~1500ppm, or 500ppm~10000ppm, or 500ppm~5000ppm, or 500ppm~4000ppm, or 500ppm~2000ppm, or 500ppm~1500ppm, or 1000ppm~10000ppm, or 1000ppm~5000ppm, or 1000ppm~4000ppm, or 1000ppm~2000ppm, or 1000ppm~1500ppm.

[0055] The monometal salt of a polyvalent inorganic acid is contained at a content 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 gives off more than one hydrogen ion among inorganic acids, and depending on the number of hydrogen ions, it can include divalent inorganic acids, trivalent inorganic acids, tetravalent inorganic acids, pentavalent inorganic acids, etc. More specifically, examples of the polyvalent inorganic acid can include sulfuric acid or 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 mixtures 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 more than 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 is 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. 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, such as 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 more, or 150°C or more, or 160°C or more, or 170°C or more, or 180°C or more, or 183°C or more, or 184°C or more, or 200°C or less, or 190°C or less, 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 (apparatus name: DSC2920, manufacturer: TA instrument). The crystallization temperature is determined from a temperature-heat flow graph obtained by scanning at a heating rate or cooling rate of 5°C / min to 15°C / min in a temperature range of 0°C to 250°C. More specifically, the crystallization temperature (T c ) is determined by peak analysis of the cooling curve of the heat flow during the first cooling step.

[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 a lower limit of an intrinsic viscosity 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 limit numerical range and the lower limit numerical range may be combined to satisfy a numerical range between the lower limit and the upper limit. As an example of the numerical range between the lower limit and the upper limit, the intrinsic viscosity measured by DIN-53728-3 may be 0.5 dL / g to 10 dL / g.

[0064] The applications of the polyester polymer are not particularly limited, and the application fields of conventionally known thermoplastic polyester polymers can be introduced without limitation, but for example, the polyester polymer can be used in various applications such as automobile parts, automobile interior materials, automobile exterior materials, cables, wires, hoses, tubes, antenna covers, leisure goods, and sporting goods.

[0065] The molding process for such applications is not limited, and various conventional 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 preparing a prepolymer by adding a catalyst to the reaction mixture after the completion of the step a) and carrying out condensation polymerization under reduced pressure; and c) a second condensation polymerization step of condensing the prepolymer under a pressure condition lower than that of the 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 realizing the effects of the present invention. Specifically, examples of diols that can be used in the present invention include 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 tricyclodecane dimethanol; but are not limited thereto. Specifically, in the present invention, the diol may be 1,4-butanediol, which is 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, etc. 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 reacting diol and dicarboxylic acid or its derivative is carried out in the presence of a catalyst (main catalyst) and a cocatalyst, and the catalyst (main catalyst) may be any suitable material known in the art. Specifically, the catalyst (main catalyst) may be a catalyst containing titanium or tin as an active metal, and 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-mentioned 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. Of these, a titanium-based catalyst such as TBT can be preferably used.

[0072] Meanwhile, in the present invention, the catalyst is added not only in the esterification reaction but also in the polycondensation step. In general, 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 a certain amount of catalyst is added at the start or during the initial esterification (or transesterification) reaction, it is not necessary to add additional catalyst in the polycondensation step.

[0073] The co-catalyst may 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 means 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 2(di) 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 2 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 dimetal salt of a polyvalent inorganic acid, a trimetal salt of a polyvalent inorganic acid, a tetrametal salt of a polyvalent inorganic acid, or a pentametal salt of a polyvalent inorganic acid, depending on the number of metal components.

[0075] Among the multiple metal salts of polyvalent inorganic acids, examples of dimetal 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 means 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 number of metal components in the chemical formula of a metal salt of a polyvalent inorganic acid is one, it is defined as a monometallic salt of a polyvalent inorganic acid. Examples of the monometallic salt of a polyvalent inorganic acid include sodium bisulfate (NaHSO4) and sodium dihydrogen phosphate (NaH2PO4).

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

[0079] Therefore, when a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid are mixed, a sufficient polymerization time shortening effect can be achieved with a smaller amount of the multimetal salt of a polyvalent inorganic acid due to the monometal salt of the polyvalent inorganic acid. On the other hand, when only one monometal salt of a polyvalent inorganic acid is used, the polymerization time of the polyester polymer increases to more than 140 minutes, which is a problem in that the polymerization time is not shortened sufficiently, and when only one multimetal salt of a polyvalent inorganic acid is used, an excessive amount of the multimetal salt of a polyvalent inorganic acid must be added to shorten the polymerization time to a sufficient level, which is a problem in that the efficiency of the process is difficult to ensure.

[0080] Specifically, the weight ratio of the multiple metal salt of a polyvalent inorganic acid to 1 part by weight of the monometal 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 multiple metal 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 of the polyester polymer by the polyvalent inorganic acid multiple metal salt is difficult to fully achieve.If the weight ratio of the polyvalent inorganic acid multiple metal 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 multiple metal salt must be added, which makes it difficult to ensure the efficiency of the process.

[0082] More specifically, the multimetal salt of the multivalent 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 3,000 ppm, based on the weight of the reaction mixture after the completion of step a). It is contained at a content of ppm to 1500ppm, or 500ppm to 10000ppm, or 500ppm to 5000ppm, or 500ppm to 4000ppm, or 500ppm to 2000ppm, or 500ppm to 1500ppm, or 1000ppm to 10000ppm, or 1000ppm to 5000ppm, or 1000ppm to 4000ppm, or 1000ppm to 2000ppm, or 1000ppm to 1500ppm.

[0083] In addition, the monometal salt of a polyvalent inorganic acid is contained in a content 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).

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

[0086] Meanwhile, in the present invention, the co-catalyst may be added in a certain amount 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 raised at 0.1° C. / min to 10° C. / min under 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 the 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, without a distillation column. Specifically, the polycondensation step is carried out after adding 50 ppm or more of a catalyst based on active metal to the reaction mixture after the step a) is completed.

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

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

[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 the completion of step a), and the mixture is stirred under reduced pressure to obtain a prepolymer.

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

[0093] If the polycondensation is carried out immediately under a high vacuum of 5 torr or less without carrying out the step b), the unreacted diol may be rapidly vaporized, causing bumping in the reactor and a rapid drop in temperature of the reactants. Also, a polyester polymer may not be obtained with a high viscosity. Therefore, in the present invention, a first polycondensation step is preliminarily carried out under relaxed conditions before the full-scale 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 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., TiO2, 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, including, but not limited to, any one or mixtures of two or more of these. As an example, a stabilizer in the form of a hindered phenol (e.g., Irganox 1330) can be introduced to increase the heat stability of the polyester polymer.

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

[0097] Also, the method for preparing the polyester polymer may 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 under reduced pressure.

[0099] In step c), the time from the start of the reaction to the time when the torque value attached to the mechanical stirrer reaches 0.8 Nm and the reaction is stopped 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. In step c), if the time from the start of the reaction to the time when the torque value attached to the mechanical stirrer reaches 0.8 Nm and the reaction is stopped is excessively increased, there is a problem that the polymerization time is difficult to sufficiently shorten, thereby reducing productivity.

[0100] The 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 condensation polymerization 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, the co-catalyst comprising: a monometallic salt of a polyvalent inorganic acid; and a multimetallic salt of a polyvalent inorganic acid.

[0102] The catalyst system can be applied to synthesize various polymers, and specific examples of the polymers are not particularly limited, and the catalyst system can be applied to any conventionally known polymers. However, for example, polyester (co)polymers, polyether ester 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, polyacrylic (co)polymers, etc. can be used. The (co)polymers include both homopolymers and copolymers.

[0103] The catalyst (main catalyst) may be any material known in the art. Specifically, the catalyst (main catalyst) may be a catalyst containing titanium or tin as an active metal, and 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-mentioned 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, a titanium-based catalyst such as TBT may be preferably used.

[0104] The co-catalyst may 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 means 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 2(di) 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 2 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 dimetal salt of a polyvalent inorganic acid, a trimetal salt of a polyvalent inorganic acid, a tetrametal salt of a polyvalent inorganic acid, or a pentametal salt of a polyvalent inorganic acid, depending on the number of metal components.

[0106] Among the multiple metal salts of polyvalent inorganic acids, examples of dimetal 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 can act as a co-catalyst to shorten the polymerization time.

[0108] The monometallic salt of a polyvalent inorganic acid means 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 number of metal components in the chemical formula of a metal salt of a polyvalent inorganic acid is one, it is defined as a monometallic salt of a polyvalent inorganic acid. Examples of the monometallic salt of a polyvalent inorganic acid include sodium bisulfate (NaHSO4) and sodium dihydrogenphosphate (NaH2PO4).

[0109] The monometal salt of a polyvalent inorganic acid acts as a co-catalyst to assist in shortening the polymerization time by the multimetal salt of a polyvalent inorganic acid, so that the polymerization time can be sufficiently shortened even with a smaller amount of the multimetal salt of a polyvalent inorganic acid, thereby improving the process efficiency.

[0110] Therefore, when a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid are mixed and used, a sufficient polymerization time shortening effect can be achieved with a smaller amount of the multimetal salt of a polyvalent inorganic acid than with the monometal salt of a polyvalent inorganic acid. On the other hand, when only one monometal salt of a polyvalent inorganic acid is used, there is a problem that the polymerization time is not shortened sufficiently, and when only one multimetal salt of a polyvalent inorganic acid is used, there is a problem that it is difficult to ensure the efficiency of the process because an excessive amount of the multimetal salt of a polyvalent inorganic acid must be added to shorten the polymerization time to a sufficient level.

[0111] Specifically, the weight ratio of the multiple metal salt of a polyvalent inorganic acid to 1 part by weight of the monometal 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 multiple metal 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 by the polyvalent inorganic acid multiple metal salt is difficult to fully achieve.If the weight ratio of the polyvalent inorganic acid multiple metal 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 multiple metal salt must be added, which makes it difficult to ensure the efficiency of the process.

[0113] More specifically, the multimetal salt of the multivalent 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 3,000 ppm, based on the weight of the reaction mixture after the completion of step a). It is contained at a content of ppm to 1500ppm, or 500ppm to 10000ppm, or 500ppm to 5000ppm, or 500ppm to 4000ppm, or 500ppm to 2000ppm, or 500ppm to 1500ppm, or 1000ppm to 10000ppm, or 1000ppm to 5000ppm, or 1000ppm to 4000ppm, or 1000ppm to 2000ppm, or 1000ppm to 1500ppm.

[0114] In addition, the monometal salt of a polyvalent inorganic acid is contained in a content 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).

[0115] The polyvalent inorganic acid is a polyprotic acid that gives off more than one hydrogen ion among inorganic acids, and depending on the number of hydrogen ions, it can include divalent inorganic acids, trivalent inorganic acids, tetravalent inorganic acids, pentavalent inorganic acids, etc. More specifically, examples of the polyvalent inorganic acid can include sulfuric acid or 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 mixtures thereof. Effect of the Invention

[0117] According to the present invention, there can be provided a polyester polymer capable of significantly shortening the polymerization time and increasing the productivity while maintaining excellent physical properties, a production method thereof, and a catalyst system thereof. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0118] The present invention will be described in more detail with reference to the following examples, however, 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 In a 2L glass reactor, 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) as a cocatalyst, and 50ppm (based on the total amount of raw materials) of sodium bisulfate (NaHSO4) were added, stirred under nitrogen for 2 hours at 230℃, and the temperature was raised to 100 to 760 torr to carry out the esterification (ES) reaction.

[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 for 30 minutes at 230°C to 240°C, and the first polycondensation (PP) reaction was carried out.

[0121] Thereafter, the second polycondensation (PC) reaction was carried out at 240°C to 250°C and 1 torr or less. During the PC reaction, the torque value attached to the mechanical stirrer increased continuously, 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 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 (Na2SO4) and sodium bisulfate (NaHSO4), 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: min) In the above 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 samples in a mixed solvent of o-cresol / 1,2-dichlorobenzene (weight ratio 1:1) and 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 above examples and comparative examples were scanned twice in a temperature range of 0°C to 250°C at a heating rate or cooling rate of 10°C / min using a differential scanning calorimetry (DSC2920, manufacturer: TA Instruments) to obtain a melting point (T m ) and crystallization temperature (T c ) was measured. The crystallization temperature (T c ) is obtained by peak analysis of the cooling curve of the heat flow during the first cooling, 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 exhibit 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 is shortened to 70 minutes or 91 minutes, which is shorter than the comparative examples having 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 a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid remaining in said polymeric matrix.

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. 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. The polyester polymer according to claim 1 , wherein the polyvalent inorganic acid comprises sulfuric acid or phosphoric acid.

6. 2. The polyester polymer of claim 1, wherein the metal of the metal salt comprises an alkali metal or an alkaline earth metal.

7. The multimetal salt of a polyvalent inorganic acid is sodium sulfate; 2. The polyester polymer according to claim 1, wherein the monometallic salt of a polyvalent inorganic acid is sodium hydrogen sulfate.

8. 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.

9. 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.

10. 2. The polyester polymer according to claim 1, wherein the monometal 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.

11. The polyester polymer according to claim 1 , wherein the polyester repeating unit has a structure represented by the following chemical formula 1: 【Chemistry 4】 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.

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

13. 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 cocatalyst; b) a first polycondensation step of preparing a prepolymer by adding a catalyst to the reaction mixture obtained after the step a) and polycondensing the mixture under reduced pressure; and c) a second polycondensation step in which the prepolymer is polycondensed under a pressure condition lower than that in step b); The method for producing a polyester polymer, wherein the co-catalyst comprises a monometallic salt of a polyvalent inorganic acid and a multimetallic salt of a polyvalent inorganic acid.

14. 14. The method for producing a polyester polymer according to claim 13, wherein in step c), the time from the start of the reaction to the time when the torque value attached to a mechanical stirrer reaches 0.8 Nm and the reaction is terminated is 95 minutes or less.

15. The method for producing a polyester polymer according to claim 13, 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.

16. The method for preparing a polyester polymer according to claim 13, 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 the completion of step a).

17. The method for producing a polyester polymer according to claim 13, wherein the monometal 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 the completion of step a).

18. The multimetal salt of a polyvalent inorganic acid is sodium sulfate; The method for producing a polyester polymer according to claim 13, wherein the monometallic salt of a polyvalent inorganic acid is sodium hydrogen sulfate.

19. Contains a catalyst and a co-catalyst, The catalyst system wherein the co-catalyst comprises a monometal salt of a polyvalent inorganic acid and a multimetal salt of a polyvalent inorganic acid.

20. The multimetal salt of a polyvalent inorganic acid is sodium sulfate; 20. The catalyst system of claim 19, wherein the monometallic salt of a polyvalent inorganic acid is sodium hydrogen sulfate.

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