Process for preparing a polyalkylene carbonate resin

Abstract

The present invention relates to a method of preparing a polyalkylene carbonate resin, and more particularly, to a method of preparing a polyalkylene carbonate resin having reduced content of cyclic carbonate as a by-product and increased proportion of repeating units comprising carbon dioxide by increasing catalyst activity.

Description

Technical Field

[0001] [Cross-references to related applications]

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0128985, filed on September 29, 2021, the entire contents of which are incorporated herein by reference.

[0003] This invention relates to a method for preparing a polyalkylene carbonate resin having a reduced content of cyclic carbonates as byproducts by increasing catalyst activity and increasing the proportion of repeating units containing carbon dioxide. Background Technology

[0004] Since the Industrial Revolution, humanity has consumed vast amounts of fossil fuels to build modern society, but environmental destruction, including deforestation, has led to an increase in atmospheric carbon dioxide concentration. As this increase contributes to the greenhouse effect, reducing the concentration of carbon dioxide in the atmosphere—which significantly contributes to global warming—is crucial, and various studies on carbon dioxide emission regulation and fixation are underway.

[0005] Recently, polyalkylene carbonate resins polymerized from carbon dioxide and epoxides have attracted attention as a biodegradable resin. Specifically, the process of preparing polyalkylene carbonate resins using carbon dioxide can reduce global warming by fixing carbon dioxide in the atmosphere, and its use as a carbon source has also been actively studied.

[0006] To prepare polyalkylene carbonate resins, a catalyst, as well as carbon dioxide and epoxides, is required. As a typical heterogeneous catalyst, bimetallic cyanide catalysts are currently being used, which consist of zinc dicarboxylic acid catalysts, such as zinc glutarate catalysts combined with dicarboxylic acid, and complexes of Co, Zn, Al, etc.

[0007] In the case of zinc glutarate catalysts, there are advantages of easy synthesis and processing, but the catalyst activity is very low, thus increasing the amount of catalyst required, and catalyst removal is difficult after the polymerization reaction. Conversely, in the case of bimetallic cyanide catalysts, there are problems such as high activity, but a low proportion of repeating carbon dioxide units in the polymerized polyalkylene carbonate resin.

[0008] Therefore, there is a need to develop a catalyst that exhibits high catalytic activity and improved carbon dioxide fixation efficiency, while also enabling stable polymerization of polyalkylene carbonates and improving the proportion of repeating carbon dioxide units in the polymerized polyalkylene carbonates.

[0009] [Existing Technical Documents]

[0010] (Patent Documents)

[0011] KR 10-2013-0102588A(2013.09.17) Summary of the Invention

[0012] Technical issues

[0013] The present invention aims to solve the above-mentioned problems and provide a method for preparing a polyalkylene carbonate resin having a high proportion of repeating units containing carbon dioxide and a reduced content of cyclic carbonates as byproducts, wherein an alkylene oxide compound and carbon dioxide are polymerized in the presence of a bimetallic cyanide catalyst containing a compound represented by Formula 9 as a complexing agent.

[0014] Technical solution

[0015] To address the aforementioned issues, this invention provides a method for preparing polyalkylene carbonate resins.

[0016] (1) This invention provides a method for preparing a polyalkylene carbonate resin with a glass transition temperature (Tg) of -10°C to 50°C and comprising repeating units represented by Formula 1 and Formula 2, the method comprising: a step of polymerizing an alkylene oxide compound and carbon dioxide in the presence of a catalyst, wherein the catalyst comprises a bimetallic cyanide compound and a complexing agent, and the complexing agent is a compound represented by Formula 9:

[0017] [Formula 1]

[0018]

[0019] [Equation 2]

[0020]

[0021] In Equations 1 and 2,

[0022] R1 to R8 are each independently hydrogen, a straight-chain alkyl group with 1 to 20 carbon atoms, a branched alkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, an alkenyl group with 2 to 20 carbon atoms, or a cycloalkyl group with 3 to 20 carbon atoms.

[0023] *Refers to the connection between repeating units, and

[0024] x and y are mole fractions, where x is between 0.70 and 1.00, y is between 0.00 and 0.30, and x + y is 1.

[0025] [Formula 9]

[0026]

[0027] R 9a and R 9b Each is independently a single bond or an alkylene group with 1 to 5 carbon atoms, wherein R 9a and R 9b At least one of them is an alkylene group with 1 to 5 carbon atoms.

[0028] R 9c and R 9d Each is independently a hydrogen atom or an alkyl group with 1 to 6 carbon atoms, and

[0029] n is an integer between 0 and 2.

[0030] (2) The present invention provides a method for preparing polyalkylene carbonate resin according to (1), wherein the polymerization is carried out in a temperature range of 30°C to 120°C.

[0031] (3) The present invention provides a method for preparing polyalkylene carbonate resin according to (1) or (2), wherein the polymerization is carried out in a pressure range of 5 bar to 50 bar.

[0032] (4) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (3), wherein the compound represented by Formula 9 is selected from cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, 1-methylcyclopentanol, 2-methylcyclopentanol, 3-methylcyclopentanol, 1-ethylcyclopentanol, 2-ethylcyclopentanol, 3-ethylcyclopentanol, 1-propylcyclopentanol, 2-propylcyclopentanol, 3-Propylcyclopentanol, 1-Butylcyclopentanol, 2-Butylcyclopentanol, 3-Butylcyclopentanol, 1-Isopropylcyclopentanol, 2-Isopropylcyclopentanol, 3-Isopropylcyclopentanol, 1-(Prop-2-yl)cyclopentanol, 2,2-Dimethylcyclopentanol, 2,3-Dimethylcyclopentanol, 3,3-Dimethylcyclopentanol, 1,2-Dimethylcyclopentanol, 1,3-Dimethylcyclopentanol, 1-Methylcyclohexanol, 1-Ethylcyclohexanol Alcohols, 1-propylcyclohexanol, 1-butylcyclohexanol, 2-methyl-1-cyclohexanol, 2-ethyl-1-cyclohexanol, 3-ethyl-1-cyclohexanol, 4-ethyl-1-cyclohexanol, 2-propyl-1-cyclohexanol, 3-propyl-1-cyclohexanol, 4-propyl-1-cyclohexanol, 2-butyl-1-cyclohexanol, 3-butyl-1-cyclohexanol, 4-butyl-1-cyclohexanol, 2-isopropyl-1-cyclohexanol, 3 -Isopropyl-1-cyclohexanol, 4-isopropyl-1-cyclohexanol, 2-tert-butyl-1-cyclohexanol, 3-tert-butyl-1-cyclohexanol, 4-tert-butyl-1-cyclohexanol, 2,3-dimethyl-1-cyclohexanol, 2,4-dimethyl-1-cyclohexanol, 3,4-dimethyl-1-cyclohexanol, 1-methylcycloheptanol, 2-methylcycloheptanol, 3-methylcycloheptanol and 4-methylcycloheptanol.

[0033] (5) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (4), wherein the compound represented by Formula 9 is selected from any one or more of cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol and cyclooctanol.

[0034] (6) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (5), wherein the bimetallic cyanide compound is derived from a metal cyanide complex and a metal salt.

[0035] (7) The present invention provides a method for preparing polyalkylene carbonate resin according to (6), wherein the metal cyanide complex is potassium hexacyanocobalt(III), potassium hexacyanoferric(II), potassium hexacyanoferric(III), calcium hexacyanoferric(III), or lithium hexacyanoiridium(III).

[0036] (8) The present invention provides a method for preparing polyalkylene carbonate resin according to (6), wherein the metal salt is selected from one or more of zinc chloride (II), zinc chloride (III), zinc bromide, zinc iodide, zinc acetate, zinc acetylacetone, zinc benzoate, zinc nitrate, ferric sulfate (II), ferric bromide (II), cobalt chloride (II), cobalt thiocyanate (II), nickel formate (II), and nickel nitrate (II).

[0037] (9) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (8), wherein the catalyst further comprises a co-complexing agent, the co-complexing agent being a compound having a hydroxyl, amino, ester or ether group at the end.

[0038] (10) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (9), wherein x is 0.90 to 1.00 and y is 0.00 to 0.10.

[0039] (11) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (10), wherein in formula 1 and formula 2, R1 to R8 are each independently hydrogen, and the glass transition temperature (Tg) is 0°C to 20°C.

[0040] (12) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (11), wherein, in Formula 1 and Formula 2, R1 to R8 are each independently a straight-chain alkyl group of 1 to 20 carbon atoms, a branched alkyl group of 3 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, or a cycloalkyl group of 3 to 20 carbon atoms, and the glass transition temperature (Tg) is 30°C to 50°C.

[0041] (13) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (12), wherein the repeating unit represented by formula 1 is represented by the following formula 3:

[0042] [Formula 3]

[0043]

[0044] In Formula 3, R1 to R4 are each independently hydrogen or a straight-chain alkyl group with 1 to 10 carbon atoms, and x and * are the same as those defined in Formula 1.

[0045] (14) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (13), wherein the repeating unit represented by formula 1 is represented by formula 4 or formula 5.

[0046] [Formula 4]

[0047]

[0048] [Formula 5]

[0049]

[0050] In Equations 4 and 5, x and * are the same as those defined in Equation 1.

[0051] (15) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (14), wherein the repeating unit represented by formula 2 is represented by formula 6.

[0052] [Formula 6]

[0053]

[0054] In Formula 6, R5 to R8 are each independently hydrogen or a straight-chain alkyl group with 1 to 10 carbon atoms, and y and * are the same as those defined in Formula 2.

[0055] (16) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (15), wherein the repeating unit represented by formula 2 is represented by formula 7 or formula 8.

[0056] [Formula 7]

[0057]

[0058] [Formula 8]

[0059]

[0060] In Equations 7 and 8, y and * are the same as those defined in Equation 2.

[0061] (17) The present invention provides a method for preparing polyalkylene carbonate resin according to any one of (1) to (16), wherein the cyclic carbonate content is from 0.5% by weight to 15.0% by weight based on the total weight of the polyalkylene carbonate resin.

[0062] Beneficial effects

[0063] In the method for preparing polyalkylene carbonate resin according to the present invention, an alkylene oxide compound and carbon dioxide are polymerized in the presence of a bimetallic cyanide catalyst containing a compound represented by Formula 9 as a complexing agent, and a polyalkylene carbonate resin having an increased proportion of repeating units containing carbon dioxide, a reduced content of cyclic carbonates as byproducts, and an increased glass transition temperature can be prepared. Detailed Implementation

[0064] It should be understood that the words or terms used in the specification and claims of this invention should not be construed as having the meanings defined in common dictionaries. It should be understood that, based on the principle that inventors can appropriately define the meanings of words to best illustrate the invention, the words or terms should be understood to have meanings consistent with their meanings in the technical concept of this invention.

[0065] The term "alkyl" as used in this invention may refer to a monovalent aliphatic saturated hydrocarbon.

[0066] The term "aryl" as used in this invention can refer to cyclic aromatic hydrocarbons and can include both monocyclic aromatic hydrocarbons in which one ring is formed and polycyclic aromatic hydrocarbons in which two or more rings are combined.

[0067] The term "alkenyl" as used in this invention may refer to a monovalent aliphatic unsaturated hydrocarbon containing one, two or more double bonds.

[0068] The term "cycloalkyl" as used in this invention can include both cyclic saturated hydrocarbons and cyclic unsaturated hydrocarbons containing one, two or more unsaturated bonds.

[0069] The invention will be described in more detail below.

[0070] Methods for preparing polyalkylene carbonate

[0071] The present invention provides a method for preparing polyalkylene carbonate resin, wherein the glass transition temperature (Tg) of the polyalkylene carbonate resin is from -10°C to 50°C, and the resin comprises repeating units represented by Formula 1 and repeating units represented by Formula 2.

[0072] [Formula 1]

[0073]

[0074] [Equation 2]

[0075]

[0076] In Equations 1 and 2,

[0077] R1 to R8 are each independently hydrogen, a straight-chain alkyl group with 1 to 20 carbon atoms, a branched alkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, an alkenyl group with 2 to 20 carbon atoms, or a cycloalkyl group with 3 to 20 carbon atoms.

[0078] *Refers to the connection between repeating units.

[0079] x and y are mole fractions, where x is from 0.70 to 1.00, y is from 0.00 to 0.30, and x+y is 1.

[0080] A method for preparing polyalkylene carbonate resin according to one embodiment of the present invention includes the step of polymerizing an alkylene oxide compound and carbon dioxide in the presence of a catalyst, said catalyst comprising a bimetallic cyanide compound and a complexing agent, wherein said complexing agent may be a compound represented by Formula 9.

[0081] [Formula 9]

[0082]

[0083] R 9a and R 9b Each is independently a single bond or an alkylene group with 1 to 5 carbon atoms, wherein R 9a and R 9b At least one of them is an alkylene group with 1 to 5 carbon atoms.

[0084] R 9c and R 9d Each is independently a hydrogen atom or an alkyl group with 1 to 6 carbon atoms, and

[0085] n is an integer between 0 and 2.

[0086] Typically, the bimetallic cyanide catalyst uses ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, or polyalkylene glycols to improve catalyst activity.

[0087] Specifically, tert-butanol is the most widely used complexing agent for preparing bimetallic cyanide catalysts. However, if polyalkylene carbonate resins are polymerized under a bimetallic cyanide catalyst prepared with tert-butanol, the problem is that the resulting polyalkylene carbonate resins contain a low proportion of repeating carbon dioxide units.

[0088] In another embodiment, to increase the proportion of repeating carbon dioxide units in the polymer obtained by copolymerizing epoxides with carbon dioxide, a bimetallic cyanide catalyst comprising C2 to C20 unsaturated alcohols has been developed and used as the copolymerization catalyst. The C2 to C20 unsaturated alcohols may have cycloalkyl groups as complexing ligands. However, the improvement in the proportion of repeating carbon dioxide units in the prepared polymer is not significant. In another embodiment, a bimetallic cyanide catalyst comprising cyclic polyols is used as a complexing agent in the copolymer. However, in this case, due to the high melting point of the cyclic polyols, the catalyst is solid at room temperature and cannot be used as a single complexing agent; instead, another complexing agent, such as tert-butyl glycol, is essentially required. Furthermore, the problem remains that the proportion of repeating carbon dioxide units in the prepared polymer is still not high.

[0089] However, the bimetallic cyanide catalyst of the present invention is prepared by using a cycloalkane-type alcohol with a bulk structure as a complexing agent, and the crystal structure of the catalyst can be diverse, including cubic, amorphous and monoclinic crystals, thus exhibiting the effect of appropriately controlling the reaction rate of epoxide and carbon dioxide.

[0090] Specifically, according to one embodiment of the invention, the catalyst comprises a compound represented by Formula 9 as a complexing agent, and in Formula 9, R 9a and R 9b Each can be an alkylene group with a single bond or 1 to 3 carbon atoms, wherein R 9a and R 9b At least one of them is an alkylene group with 1 to 3 carbon atoms, R 9c and R 9d Each is independently a hydrogen atom or an alkyl group with 1 to 4 carbon atoms, and n can be an integer from 0 to 2.

[0091] In another implementation, in Equation 9, R 9a and R 9b Each can be an alkylene group with a single bond or 1 to 3 carbon atoms, R 9a and R 9b At least one of them can be an alkylene group with 1 to 3 carbon atoms, R 9c It can be a hydrogen atom, and n can be 0.

[0092] In another embodiment, the complexing agent may be a cycloalkyl alcohol with 3 to 12 carbon atoms, specifically, a cycloalkyl alcohol with 4 to 10 carbon atoms or 5 to 7 carbon atoms.

[0093] In another embodiment, the compound represented by Formula 9 may be selected from cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, 1-methylcyclopentanol, 2-methylcyclopentanol, 3-methylcyclopentanol, 1-ethylcyclopentanol, 2-ethylcyclopentanol, 3-ethylcyclopentanol, 1-propylcyclopentanol, 2-propylcyclopentanol, 3-propylcyclopentanol, 1-butylcyclopentanol, 2-butylcyclopentanol, 3-butylcyclopentanol, 1-isopropylcyclopentanol, 2-isopropylcyclopentanol, 3-isopropylcyclopentanol, 1-(propyl-2-yl)cyclopentanol, 2,2-dimethylcyclopentanol, 2,3-dimethylcyclopentanol, 3,3-dimethylcyclopentanol, 1,2-dimethylcyclopentanol, 1,3-dimethylcyclopentanol, 1-methylcyclohexanol, 1-ethylcyclohexanol, 1-propylcyclohexanol, 1-butylcyclohexanol, 1-ethylcyclohexanol, 1-propylcyclohexanol, 1-butylcyclohexanol, 1-ethylcyclohexanol, 1-propylcyclohexanol, 1-ethylcyclohexanol, 1-propylcyclohexanol, 1-butylcyclohexanol, 2-ethylcyclopentanol, 2-ethylcyclopentanol, 3-ethylcyclohexanol, 1-propylcyclohexanol, 1 ... Alcohols, 2-methyl-1-cyclohexanol, 2-ethyl-1-cyclohexanol, 3-ethyl-1-cyclohexanol, 4-ethyl-1-cyclohexanol, 2-propyl-1-cyclohexanol, 3-propyl-1-cyclohexanol, 4-propyl-1-cyclohexanol, 2-butyl-1-cyclohexanol, 3-butyl-1-cyclohexanol, 4-butyl-1-cyclohexanol, 2-isopropyl-1-cyclohexanol, 3-isopropyl-1-cyclohexanol Hexanol, 4-isopropyl-1-cyclohexanol, 2-tert-butyl-1-cyclohexanol, 3-tert-butyl-1-cyclohexanol, 4-tert-butyl-1-cyclohexanol, 2,3-dimethyl-1-cyclohexanol, 2,4-dimethyl-1-cyclohexanol, 3,4-dimethyl-1-cyclohexanol, 1-methylcycloheptanol, 2-methylcycloheptanol, 3-methylcycloheptanol, and 4-methylcycloheptanol are any one or more of these.

[0094] In another embodiment, the compound represented by Formula 9 may be any one or more selected from cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, and cyclooctanol.

[0095] Furthermore, the catalyst comprises a bimetallic cyanide compound, which may be derived from a metal cyanide complex and a metal salt, and the metal cyanide complex may exhibit water-soluble properties. Specifically, the metal cyanide complex may be represented by Formula 10.

[0096] [Formula 10]

[0097] Y a M`(CN) b

[0098] In Formula 10, M' can be one or more selected from Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ir(III), Ni(II), Rh(III), Ru(II), V(V), and V(IV), preferably one or more selected from Co(II), Co(III), Fe(II), Fe(III), Cr(III), Ir(III), and Ni(II). Y can be an alkali metal ion or an alkaline earth metal ion. a is an integer from 1 to 4, b is an integer from 4 to 6, and the values ​​of a and b can be chosen such that the metal cyanide complex is electrically neutral.

[0099] In another embodiment, the metal cyanide complex may be potassium hexacyanocobalt(III), potassium hexacyanoferric(II), potassium hexacyanoferric(III), calcium hexacyanoferric(III), or lithium hexacyanoiridium(III), preferably potassium hexacyanocobalt(III).

[0100] The metal salt can exhibit water-soluble properties. Specifically, the metal salt can be represented by Formula 11.

[0101] [Equation 11]

[0102] M(X) n

[0103] In Formula 11, M is a transition metal, preferably selected from one or more of Zn(II), Fe(II), Ni(II), Mn(II), Co(II), Sn(II), Pb(II), Fe(III), Mo(IV), Mo(VI), Al(III), V(V), V(IV), Sr(II), W(IV), W(VI), Cu(II), and Cr(III), more preferably selected from one or more of Zn(II), Fe(II), Co(II), and Ni(II). X is an anion selected from halides, hydroxides, sulfates, carbonates, cyanides, oxalates, thiocyanates, isocyanates, isothiocyanates, carboxylates, and nitrates. The value of n satisfies the valence state of M.

[0104] In another embodiment, the metal salt may be zinc(II) chloride, zinc(III) chloride, zinc bromide, zinc iodide, zinc acetate, zinc acetylacetone, zinc benzoate, zinc nitrate, ferric sulfate(II), ferric bromide(II), cobalt(II) chloride, cobalt(II) thiocyanate, nickel(II) formate, nickel(II) nitrate, and mixtures thereof, preferably zinc(II), zinc(III) chloride, zinc bromide, or zinc iodide.

[0105] The catalyst according to the present invention can be represented by Formula 12.

[0106] [Equation 12]

[0107] M 2 p [M 1 (CN)6] q ·dM 2 (X)r·eL·fH2O

[0108] In Equation 12, M 1 and M 2 Each of these elements is an independent transition metal, X is an anion, and L is cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, or cyclooctanol. p, q, d, r, e, and f are each an independent integer from 1 to 6.

[0109] More specifically, the catalyst according to the invention can be represented by Formula 13.

[0110] [Equation 13]

[0111] Zn3[Co(CN)6]2·gZnCl2·hL·iH2O

[0112] In Equation 13, L is cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, or cyclooctanol, and g, h, and i are each independent integers from 1 to 6.

[0113] The catalyst of the present invention may further comprise a co-complexing agent, and the co-complexing agent may be a compound having a hydroxyl, amino, ester or ether group at the end.

[0114] The complexing agent can enhance the activity of the catalyst and may be, for example, selected from polyacrylamide, poly(acrylamide-co-acrylic acid), polyacrylic acid, poly(acrylic acid-co-maleic acid), polyacrylonitrile, alkyl polyacrylate, alkyl polymethacrylate, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl acetate, polyvinyl alcohol, poly-N-vinylpyrrolidone, poly(N-vinylpyrrolidone-co-acrylic acid), polyvinyl methyl ketone, poly(4-vinylphenol), poly(acrylic acid-co-styrene), oxazoline polymer, polyalkylimide, maleic acid, maleic anhydride copolymer, hydroxyethyl cellulose, polyacetal, glycidyl ether, glycoside, carboxylic acid ester of polyol, gallic acid, ester and amide.

[0115] In addition, the complexing agent may be a compound prepared by ring-opening polymerization of cyclic ether compounds, epoxy polymers or oxobutane polymers, for example, selected from one or more of polyethers, polyesters, polycarbonates, polyalkylene glycols, polyalkylene glycol dehydrated sorbitol esters, and polyalkylene glycol glycidyl ethers.

[0116] Furthermore, the polyalkylene carbonate resin of the present invention can be prepared by polymerizing an alkylene oxide compound and carbon dioxide, and there are no specific limitations on the polymerization method; however, solution polymerization is preferred. Solution polymerization allows for appropriate control of the heat of reaction and facilitates the control of the weight-average molecular weight or viscosity of the target polyalkylene carbonate resin.

[0117] The catalyst and the alkylene oxide compound can be used in weight ratios of 1:100 to 1:8000, 1:300 to 1:6000, or 1:1000 to 1:4000. Within these ranges, it is possible to obtain effects such as high catalyst activity, minimization of byproducts, and minimization of back-biting phenomena in the prepared polyalkylene carbonate resin due to heat.

[0118] Furthermore, the polymerization reaction of alkyl epoxides and carbon dioxide is carried out within a temperature range of 30°C to 120°C, 40°C to 110°C, or 50°C to 100°C. If these ranges are met, the polymerization time of alkyl epoxides and carbon dioxide can be controlled within 24 hours, thereby improving production productivity.

[0119] Furthermore, the polymerization of alkylene oxides and carbon dioxide can be carried out within pressure ranges of 5 to 50 bar, 10 to 40 bar, or 15 to 30 bar. If these ranges are met, it is possible to achieve a high proportion of repeating units containing carbon dioxide in the prepared polyalkylene carbonate resin, as well as a reduction in byproducts containing cyclic carbonates.

[0120] The alkyl oxide compound may be one or more compounds selected from: alkyl oxides of 2 to 20 carbon atoms that are unsubstituted or substituted with halogens or alkyl groups of 1 to 5 carbon atoms; alkyl oxides of 4 to 20 carbon atoms that are unsubstituted or substituted with halogens or alkyl groups of 1 to 5 carbon atoms; and styrene oxide of 8 to 20 carbon atoms that are unsubstituted or substituted with halogens or alkyl groups of 1 to 5 carbon atoms, for example, one or more compounds selected from: ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene oxide, 1,2-epoxy-7-octene, epifluoropropane, epichlorohydrin. Epichlorohydrin, isopropyl glycidyl ether, butyl glycidyl ether, tert-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, α-pinene oxide, 2,3-epoxynorbornene, limonene oxide, dieldrin, 2,3-epoxypropylbenzene, styrene oxide, phenylepoxypropane, stilbene oxide, chlorostilbene oxide, dichlorostilbene oxide, 1,2-epoxy-3-phenoxypropane, benzyloxymethyl ethylene oxide, glycidyl-methylphenyl ether, chlorophenyl-2,3-epoxypropyl ether, epichlorophenyl methoxyphenyl ether, biphenyl glycidyl ether, and glycidyl naphthalene ether.

[0121] In addition, in the case of solution polymerization of alkyl epoxides and carbon dioxide, the alkyl epoxides and solvents can be mixed, and the solvent can be one or more selected from dichloromethane, dichloroethane, trichloroethane, tetrachloroethane, chloroform, acetonitrile, propionitrile, dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, nitromethane, 1,4-dioxane, hexane, toluene, tetrahydrofuran, methyl ethyl ketone, methyl methacrylate, methyl methacrylate, methyl isobutyl ketone, acetone, cyclohexanone, trichloroethylene, methyl acetate, vinyl acetate, ethyl acetate, propyl acetate, butyrolactone, caprolactone, nitropropane, benzene, styrene, xylene, and methyl propasol. Preferably, using dichloromethane as a solvent can make the polymerization reaction more efficient.

[0122] The solvent and the alkylene oxide compound can be used in a weight ratio of 1:0.1 to 1:100, 1:1 to 1:100, or 1:1 to 1:10. Within this range, the solvent can suitably serve as a reaction medium, thereby improving the productivity of polyalkylene carbonate resins and minimizing byproducts generated during the preparation process.

[0123] In addition, the polyalkylene carbonate resin prepared by the preparation method according to one embodiment of the present invention can have a glass transition temperature (Tg) of -10°C to 50°C, and can contain repeating units represented by Formula 1 and repeating units represented by Formula 2.

[0124] The polyalkylene carbonate resin obtained by the preparation method described herein will be explained in more detail below.

[0125] The polyalkylene carbonate resin prepared by the preparation method according to one embodiment of the present invention has a glass transition temperature (Tg) of -10°C to 50°C and contains repeating units represented by Formula 1 and repeating units represented by Formula 2.

[0126] [Formula 1]

[0127]

[0128] [Equation 2]

[0129]

[0130] In Formulas 1 and 2, R1 to R8 are each independently hydrogen, a straight-chain alkyl group of 1 to 20 carbon atoms, a branched alkyl group of 3 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, or a cycloalkyl group of 3 to 20 carbon atoms, * denotes the connecting portion between repeating units, x and y are mole fractions, where x is 0.70 to 1.00, y is 0.00 to 0.30, and x+y is 1.

[0131] In addition, "branched alkyl" can refer to alkyl groups that exhibit branched structure in all their bonding states.

[0132] Additionally, x can be from 0.80 to 1.00, and y can be from 0.00 to 0.20; preferably, x can be from 0.90 to 1.00, and y can be from 0.00 to 0.10. If the above ranges are met, the carbon dioxide fixation rate is high, the reduction of the greenhouse effect is effective, and its biodegradability is advantageous. Furthermore, if the polyalkylene carbonate resin according to the present invention is used to manufacture a film, it can exhibit low oxygen permeability and achieve excellent barrier properties.

[0133] The polyalkylene carbonate resin may include polyvinyl carbonate resin, polypropylene carbonate resin, polypentenyl carbonate resin, polyhexenyl carbonate resin, polyoctenyl carbonate resin, polycyclohexenyl carbonate resin, or copolymers thereof. Furthermore, in Formula 1, R1 to R8 may each be independently hydrogen, a straight-chain alkyl group with 1 to 20 carbon atoms, a branched alkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, an alkenyl group with 2 to 20 carbon atoms, or a cycloalkyl group with 3 to 20 carbon atoms, and may be ultimately appropriately selected considering the desired physical properties of the resin.

[0134] In addition, the repeating unit represented by Equation 1 can be represented by Equation 3.

[0135] [Formula 3]

[0136]

[0137] In Formula 1, R1 to R4 are each independently hydrogen or a straight-chain alkyl group with 1 to 10 carbon atoms, and x and * are the same as defined in Formula 1.

[0138] More specifically, the repeating unit represented by Equation 1 can be represented by Equation 4 or Equation 5.

[0139] [Formula 4]

[0140]

[0141] [Formula 5]

[0142]

[0143] In Equations 4 and 5, x and * are the same as those defined in Equation 1.

[0144] Furthermore, the repeating unit represented by Equation 2 can be represented by Equation 6.

[0145] [Formula 6]

[0146]

[0147] In Formula 6, R5 to R8 are each independently hydrogen or a straight-chain alkyl group with 1 to 10 carbon atoms, and y and * are the same as those defined in Formula 2.

[0148] More specifically, the repeating unit represented by Equation 2 can be represented by Equation 7 or Equation 8.

[0149] [Formula 7]

[0150]

[0151] [Formula 8]

[0152]

[0153] In Equations 7 and 8, y and * are the same as those defined in Equation 2.

[0154] The glass transition temperature (Tg) of the polyalkylene carbonate resin of the present invention is -10°C to 50°C, 0°C to 50°C, or 10°C to 50°C. If the above ranges are met, the polyalkylene carbonate resin can have excellent processing properties at room temperature.

[0155] In another embodiment, the glass transition temperature (Tg) of the polyalkylene carbonate resin in which R1 to R8 in Formula 1 and Formula 2 are each independently hydrogen can be from 0°C to 20°C or from 0°C to 15°C.

[0156] In another embodiment, the glass transition temperature (Tg) of the polyalkylene carbonate resin, wherein R1 to R8 in Formula 1 and Formula 2 are each independently a straight-chain alkyl group with 1 to 20 carbon atoms, a branched alkyl group with 3 to 20 carbon atoms, an aryl group with 6 to 20 carbon atoms, an alkenyl group with 2 to 20 carbon atoms, or a cycloalkyl group with 3 to 20 carbon atoms, can be 30°C to 50°C or 35°C to 50°C.

[0157] Furthermore, based on the total weight of the polyalkylene carbonate resin of the present invention, the content of the cyclic carbonate can be from 0.5 wt% to 15.0 wt%, from 0.5 wt% to 10.0 wt%, or from 0.5 wt% to 5.0 wt%. If the above ranges are met, the defects caused by the deterioration of the glass transition temperature due to the cyclic carbonate acting as a softener can be minimized, and the effect of excellent physical properties can be achieved.

[0158] The cyclic carbonate content can be determined by using... 1 The H-NMR spectrometer (500MHz spectrometer, Jeol Co.) was used to measure the 10 mg polyalkylene carbonate resin sample dissolved in chloroform-d6 solvent. Specifically, the measurement was performed using... 1 The results of H-NMR spectroscopy confirmed the peak near 4.5 ppm as the cyclic carbonate peak, and the cyclic carbonate content could be calculated according to Formula 1 by using the carbonate peak area value and the ether peak area value.

[0159] [Formula 1]

[0160]

[0161] In Formula 1, the contents of A, B, C, N and CO2 can be defined as follows.

[0162] A = Peak area of ​​cyclic carbonate, B = Peak area of ​​carbonate, C = Peak area of ​​ether, N = [Molar mass of epoxide / (44 + Molar mass of epoxide)], CO2 content = (Molar fraction of carbonate unit × 44) / [(Molar fraction of carbonate unit × 44) + (Molar mass of epoxide × 100)]

[0163] The present invention will be specifically described below through specific embodiments. However, the following embodiments are for illustrative purposes only, and the scope of the present disclosure is not limited thereto.

[0164] Preparation example of bimetallic cyanide catalysts

[0165] Preparation Example 1

[0166] In a 500 ml beaker, 11.45 g of zinc chloride, 30 ml of distilled water, and 39 g of cyclohexanol were mixed to prepare a first mixture solution. In a 250 ml beaker, 4 g of potassium hexacyanocobalaate was dissolved in 100 ml of distilled water to prepare a second mixture solution. In a 100 ml beaker, 5 g of polypropylene glycol (Mw = 3,000) and 23 g of cyclohexanol were dissolved in 2 ml of distilled water to prepare a third mixture solution. Using a mechanical stirrer, the second mixture solution was added dropwise to the first mixture solution over 1 hour at 25°C, and the third mixture solution was immediately added, followed by a reaction over 1 hour. The mixture products were then separated using a high-speed centrifuge, and the separated precipitate was washed twice with a mixture of 70 ml of distilled water and 70 ml of cyclohexanol. Then, the precipitate was washed with 140 ml of cyclohexanol and dried in a vacuum oven at 80 °C for 12 hours to finally obtain 6.2 g of bimetallic cyanide catalyst.

[0167] Preparation Example 2

[0168] Except for the use of cyclopentanol instead of cyclohexanol in Preparation Example 1, the same method as in Preparation Example 1 was performed to finally obtain 6.0 g of bimetallic cyanide catalyst.

[0169] Comparative Preparation Example 1

[0170] Except that tert-butanol was used instead of cyclohexanol in Preparation Example 1, the same method as in Preparation Example 1 was performed to finally obtain 6.5 g of bimetallic cyanide catalyst.

[0171] Comparative Preparation Example 2

[0172] Except that 2-methyl-3-buten-2-ol was used instead of cyclohexanol in Preparation Example 1, the same method as in Preparation Example 1 was performed to finally obtain 6.5 g of bimetallic cyanide catalyst.

[0173] Comparative Preparation Example 3

[0174] Except that 1,5-cyclooctanediol was used instead of cyclohexanol in Preparation Example 1, the same method as in Preparation Example 1 was performed to finally obtain 6.5 g of bimetallic cyanide catalyst.

[0175] Example

[0176] Example 1

[0177] 10 mg of the bimetallic cyanide catalyst prepared in Preparation Example 1, 20 g of ethylene oxide, and an equal amount of dichloromethane solvent were added to a high-pressure reactor. Carbon dioxide was then injected into the reactor at a flow rate of 36 L / min, and a pressure of 30 bar was applied. The polymerization reaction was carried out at 65 °C for 12 hours. After the reaction, unreacted carbon dioxide was removed. The product was then diluted in 200 ml of dichloromethane solvent, unreacted ethylene oxide was removed by vacuum evaporation, and the product was dried in a vacuum oven at 40 °C for 12 hours to obtain 24.3 g of polyvinyl carbonate resin.

[0178] Example 2

[0179] Except for using propylene oxide instead of ethylene oxide in Example 1, the same method as in Example 1 was performed to finally obtain 32.29 g of polypropylene carbonate resin.

[0180] Example 3

[0181] Except that the polymerization reaction was carried out at 85°C instead of 65°C in Example 1, the same method as in Example 1 was performed to finally obtain 25.6 g of polyvinyl carbonate resin.

[0182] Example 4

[0183] Except for using propylene oxide instead of ethylene oxide in Example 3, the same method as in Example 3 was performed to finally obtain 30.5 g of polypropylene carbonate resin.

[0184] Example 5

[0185] Except that the polymerization reaction was carried out at 105°C instead of 65°C in Example 1, the same method as in Example 1 was performed to finally obtain 22.8 g of polyvinyl carbonate resin.

[0186] Example 6

[0187] Except for using propylene oxide instead of ethylene oxide in Example 5, the same method as in Example 5 was performed to finally obtain 23.2 g of polypropylene carbonate resin.

[0188] Example 7

[0189] Except that in Example 3, the bimetallic cyanide catalyst prepared in Preparation Example 2 was used instead of the bimetallic cyanide catalyst prepared in Preparation Example 1, the same method as in Example 3 was performed to finally obtain 30.0 g of polyvinyl carbonate resin.

[0190] Example 8

[0191] Except that propylene oxide was used instead of ethylene oxide in Example 7, and the polymerization reaction was carried out at 105°C instead of 85°C, the same method as in Example 7 was performed to finally obtain 30.7 g of polyvinyl carbonate resin.

[0192] Comparative Example 1

[0193] Except that in Example 1 the bimetallic cyanide catalyst prepared in Comparative Preparation Example 1 was used instead of the bimetallic cyanide catalyst prepared in Preparation Example 1, the same method as in Example 1 was performed to finally obtain 8.15 g of polyvinyl carbonate resin.

[0194] Comparative Example 2

[0195] Except that propylene oxide was used instead of ethylene oxide in Comparative Example 1, the same method as in Comparative Example 1 was performed to finally obtain 10.2 g of polypropylene carbonate resin.

[0196] Comparative Example 3

[0197] Except that the polymerization reaction was carried out at 85°C instead of 65°C in Comparative Example 1, the same method as in Comparative Example 1 was performed to finally obtain 11.7 g of polyvinyl carbonate.

[0198] Comparative Example 4

[0199] Except that propylene oxide was used instead of ethylene oxide in Comparative Example 3, the same method as in Comparative Example 3 was performed to finally obtain 23.6 g of polypropylene carbonate resin.

[0200] Comparative Example 5

[0201] Except that the polymerization reaction was carried out at 105°C instead of 65°C in Comparative Example 1, the same method as in Comparative Example 1 was performed to finally obtain 13.4 g of polyvinyl carbonate.

[0202] Comparative Example 6

[0203] Except that propylene oxide was used instead of ethylene oxide in Comparative Example 5, the same method as in Comparative Example 5 was performed to finally obtain 23.2 g of polypropylene carbonate resin.

[0204] Comparative Example 7

[0205] Except that in Example 3, the bimetallic cyanide catalyst prepared in Comparative Preparation Example 2 was used instead of the bimetallic cyanide catalyst prepared in Preparation Example 1, the same method as in Example 3 was performed to finally obtain 12.1 g of polyvinyl carbonate resin.

[0206] Comparative Example 8

[0207] Except that in Example 3 the bimetallic cyanide catalyst prepared in Comparative Preparation Example 3 was used instead of the bimetallic cyanide catalyst prepared in Preparation Example 1, the same method as in Example 3 was performed to finally obtain an effective amount of polyvinyl carbonate resin.

[0208] Experimental Example 1

[0209] The types of alkylene oxide compounds and catalyst compositions used in Examples 1 to 8 and Comparative Examples 1 to 8, as well as the polymerization temperatures of the polyalkylene carbonate resins, are shown in Table 1. Additionally, the activities of the catalysts used in Examples 1 to 8 and Comparative Examples 1 to 8 were measured and are shown in Table 1 below. Furthermore, the mole fraction of carbonate units and the glass transition temperature of the polyalkylene carbonate resins obtained in Examples 1 to 8 and Comparative Examples 1 to 8 were measured and are shown in Tables 1 and 2 below.

[0210] *Catalyst activity (g-polymer / g-catalyst): The weight of the polymerized polyalkylene carbonate resin and the amount of catalyst are measured. The catalyst activity is calculated using the measured values ​​according to Formula 2 below.

[0211] [Formula 2]

[0212] Catalyst activity (g-polymer / g-catalyst) = Weight of polymerized polyalkylene carbonate resin (g) / Amount of catalyst (g)

[0213] *Molar fraction (mol%) of carbonate unit: Using a 1H-NMR spectrometer (500MHz spectrometer, Jeol Co.), 10 mg of polyalkylene carbonate resin samples obtained from Examples 1 to 6 and Comparative Examples 1 to 4 were dissolved in chloroform-d6 solvent and then measured. The measurement results confirmed that the carbonate peak was observed in the range of 3.2 ppm to 3.9 ppm, and the ether peak in the range of 4.2 ppm. The molar fraction of the carbonate unit was calculated using the carbonate peak area and the ether peak area according to Formula 3 below.

[0214] [Formula 3]

[0215] Mole fraction (mol%) of carbonate units = [(carbonate peak area) / (carbonate peak area + ether peak area)] × 100

[0216] *Glass transition temperature (°C): Differential scanning calorimetry (DSC) analysis was performed on the polyalkylene carbonate resins obtained in Examples 1 to 8 and Comparative Examples 1 to 8. Specifically, a Q20 system from TA Instrument Co. was used, and the temperature was increased from -40°C to 200°C at a heating rate of 10°C / min under a flowing N2 atmosphere. The glass transition temperature was confirmed from the results of the DSC thermograms.

[0217] [Table 1]

[0218]

[0219] [Table 2]

[0220]

[0221] As shown in Tables 1 and 2, in Examples 1 to 8, the resins prepared by using a bimetallic cyanide catalyst containing a compound represented by Formula 9 as a complexing agent exhibited an increased glass transition temperature and an increased molar ratio of carbonate units in the polymerized polyalkylene carbonate by 1.34 to 5.22 times compared to Comparative Examples 1 to 8, which prepared the same polyalkylene carbonate resins using the same epoxide.

[0222] Experimental Example 2

[0223] The processing properties of the polyalkylene carbonate resins in the Examples and Comparative Examples were compared and analyzed. The processing properties were confirmed by manufacturing films and granules, and the results are shown in Tables 3 and 4 below.

[0224] (1) Thin film processing performance

[0225] Thin films are manufactured using resins, and their processing performance is evaluated based on the degree of film formation.

[0226] In this case, a film is produced by placing 4g of each polyalkylene carbonate resin on a hot press preheated to 180°C, compressing it at 1MPa for 5 minutes, and then compressing it at 5MPa for 1 minute. O indicates the case where a uniform and smooth film is produced, and X indicates the case where an uneven and smooth film is produced but adheres to the press.

[0227] (2) Granular processing performance

[0228] Resin is used to manufacture granules, and the processing performance is evaluated through an anti-blocking test.

[0229] Each resin was granulated using BA-PLA (Bautech Co.). 300g of the granulated polyalkylene carbonate resin was placed in a 1L polyethylene bag and left to stand at room temperature for 24 hours. When removed from the bag, O indicates no adhesion, Δ indicates easy separation by gripping force, and X indicates no separation by gripping force.

[0230] [Table 3]

[0231] Classification Thin film processing performance Granular processing performance Example 1 O Δ Example 3 O Δ Example 5 O Δ Example 7 O Δ Comparative Example 1 X X Comparative Example 3 X X Comparative Example 5 X X Comparative Example 7 X X Comparative Example 8 - -

[0232] [Table 4]

[0233] Classification Thin film processing performance Granular processing performance Example 2 O O Example 4 O O Example 6 O O Example 8 O O Comparative Example 2 O Δ Comparative Example 4 O Δ Comparative Example 6 O Δ

[0234] As shown in Table 3, it can be confirmed that the polyvinyl carbonate resins of the examples all exhibit significantly superior film properties and granule properties compared to the polyvinyl carbonate resins of the comparative examples.

[0235] Furthermore, as shown in Table 4, it can be confirmed that the polypropylene carbonate resins of the examples all exhibit significantly superior film properties and granule properties compared to the polypropylene carbonate resins of the comparative examples.

Claims

1. A method for preparing a polyalkylene carbonate resin, said polyalkylene carbonate resin having a glass transition temperature (Tg) of 0°C to 20°C and comprising repeating units represented by Formula 1 below and repeating units represented by Formula 2 below, said method comprising: The step of polymerizing alkyl epoxides and carbon dioxide in the presence of a catalyst, wherein... The catalyst comprises a bimetallic cyanide compound and a complexing agent. The complexing agent is a compound represented by the following formula 9: [Formula 1] [Equation 2] In Equations 1 and 2, R1 through R8 are each independently hydrogen. *Refers to the connection between repeating units. x and y are mole fractions, where x is between 0.70 and 1.00, y is between 0.00 and 0.30, and x + y is 1. [Formula 9] R 9a and R 9b Each is independently a single bond or an alkylene group with 1 to 5 carbon atoms, wherein R 9a and R 9b At least one of them is an alkylene group with 1 to 5 carbon atoms. R 9c and R 9d Each is independently a hydrogen atom or an alkyl group with 1 to 6 carbon atoms. n is an integer between 0 and 2.

2. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The polymerization is carried out in a temperature range of 30°C to 120°C.

3. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The polymerization is carried out in a pressure range of 5 bar to 50 bar.

4. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The compound represented by Formula 9 is selected from cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, 1-methylcyclopentanol, 2-methylcyclopentanol, 3-methylcyclopentanol, 1-ethylcyclopentanol, 2-ethylcyclopentanol, 3-ethylcyclopentanol, 1-propylcyclopentanol, 2-propylcyclopentanol, 3-propylcyclopentanol, 1-butylcyclopentanol, 2-butylcyclopentanol, 3-butylcyclopentanol, 1-isopropylcyclopentanol, 2-isopropylcyclopentanol, 3-isopropylcyclopentanol, 1-(propyl-2-yl)cyclopentanol, 2,2-dimethylcyclopentanol, 2,3-dimethylcyclopentanol, 3,3-dimethylcyclopentanol, 1,2-dimethylcyclopentanol, 1,3-dimethylcyclopentanol, 1-methylcyclohexanol, 1-ethylcyclohexanol, 1-propylcyclohexanol, 1-butylcyclohexanol, 2-methylcyclopentanol, 2-ethyl ... The following are any one or more of the following: 1-cyclohexanol, 2-ethyl-1-cyclohexanol, 3-ethyl-1-cyclohexanol, 4-ethyl-1-cyclohexanol, 2-propyl-1-cyclohexanol, 3-propyl-1-cyclohexanol, 4-propyl-1-cyclohexanol, 2-butyl-1-cyclohexanol, 3-butyl-1-cyclohexanol, 4-butyl-1-cyclohexanol, 2-isopropyl-1-cyclohexanol, 3-isopropyl-1-cyclohexanol, 4-isopropyl-1-cyclohexanol, 2-tert-butyl-1-cyclohexanol, 3-tert-butyl-1-cyclohexanol, 4-tert-butyl-1-cyclohexanol, 2,3-dimethyl-1-cyclohexanol, 2,4-dimethyl-1-cyclohexanol, 3,4-dimethyl-1-cyclohexanol, 1-methylcycloheptanol, 2-methylcycloheptanol, 3-methylcycloheptanol, and 4-methylcycloheptanol.

5. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The compound represented by Formula 9 is selected from any one or more of cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, and cyclooctanol.

6. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The bimetallic cyanide compound is derived from a metal cyanide complex and a metal salt.

7. The method for preparing polyalkylene carbonate resin according to claim 6, wherein, The metal cyanide complex is potassium hexacyanocobalt(III), potassium hexacyanoferric(II), potassium hexacyanoferric(III), calcium hexacyanoferric(III), or lithium hexacyanoiridium(III).

8. The method for preparing polyalkylene carbonate resin according to claim 6, wherein, The metal salt is selected from one or more of zinc chloride (II), zinc chloride (III), zinc bromide, zinc iodide, zinc acetate, zinc acetylacetone, zinc benzoate, zinc nitrate, ferric sulfate (II), ferric bromide (II), cobalt chloride (II), cobalt thiocyanate (II), nickel formate (II), and nickel nitrate (II).

9. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The catalyst also contains a complexing agent. The complexing agent is a compound having a hydroxyl, amino, ester, or ether group at the end.

10. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, x is between 0.90 and 0.95, and y is between 0.05 and 0.

10.

11. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The repeating unit represented by Equation 1 is represented by Equation 4 below: [Formula 4] In Equation 4, x and * are the same as those defined in Equation 1.

12. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, The repeating unit represented by Equation 2 is represented by Equation 7 below: [Formula 7] In Equation 7, y and * are the same as those defined in Equation 2.

13. The method for preparing polyalkylene carbonate resin according to claim 1, wherein, Based on the total weight of the polyalkylene carbonate resin, the cyclic carbonate content is from 0.5% by weight to 15.0% by weight.

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