Method for producing vinyl chloride copolymers

Abstract

The present invention relates to a method for producing a vinyl chloride copolymer by copolymerizing a vinyl chloride polymer with a polymerizable monomer, which can produce a highly heat-resistant vinyl chloride copolymer by optimizing the ratio of repeating units in a polyvinyl chloride chain to a reducing agent, a monomer, a catalyst, and a ligand.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0139524 filed on October 26, 2022, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method for producing a highly functional vinyl chloride copolymer using atom transfer radical polymerization (hereinafter abbreviated as ATRP).

Background Art

[0003] Polyvinyl chloride resin is a typical thermoplastic resin, which has strong flexibility and abrasion resistance and is easy to be colored in various colors, so it is widely used in various product fields. Polyvinyl chloride resin is produced by polymerizing vinyl chloride monomer, but vinyl chloride monomer has poor reactivity with other types of monomers and is not much utilized in the form of a copolymer, and is mainly utilized in the form of a homopolymer such as polyvinyl chloride.

[0004] Therefore, as a method for complementing the inferior physical properties of polyvinyl chloride, the method of blending and using polyvinyl chloride with other types of polymers having excellent required physical properties is most frequently used. However, such a method not only requires another facility for blending, but also causes other problems in that when the compatibility between the blended polymer and polyvinyl chloride is poor, the desired physical properties cannot be achieved or the blending itself is not easy.

[0005] As an alternative to such blending methods, copolymerization using atomic transfer radical polymerization (ATRP) is being researched. ATRP is a method in which polymerizable monomers are further radically polymerized onto polymerized polyvinyl chloride. This allows for copolymerization of polymerizable monomers such as styrene and methyl methacrylate with polyvinyl chloride, and such monomer copolymerization can compensate for the inferior properties of the polymer itself. However, even when applying ATRP, the properties of the copolymer produced can differ depending on conditions such as the type and amount of catalyst used, the type and amount of reducing agent used, the type and amount of ligand used, and the polymerization temperature. Therefore, in-depth research is needed on copolymerization methods that can produce optimal vinyl chloride copolymers. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] KR10-2013-0136936A(2013.12.13) [Patent Document 2] KR10-2014-0125134A(2014.10.28) [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to solve the problems of the prior art described above, and provides a method for producing vinyl chloride copolymers using ATRP, which optimizes the ratio of repeating units in the polyvinyl chloride chain to the reducing agent, monomer, catalyst, and ligand, thereby enabling the production of highly functional, particularly highly heat-resistant, vinyl chloride copolymers. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a method for producing vinyl chloride copolymers. Specifically, (1) the present invention provides a method for producing a vinyl chloride copolymer, comprising the steps of (S1) adding a reducing agent, a polymerizable monomer, a catalyst, and a ligand to a solution containing polyvinyl chloride, and (S2) raising the temperature of the solution to carry out a polymerization reaction, wherein the molar ratio of repeating units in the chain of polyvinyl chloride in the solution to the added catalyst is 1000:0.3 to 1000:0.6.

[0009] (2) The present invention provides a method for producing a vinyl chloride copolymer as described in (1), wherein the catalyst is one or more selected from the group consisting of Cu(0), Fe(0), Cu2Te, Cu2Se, CuCl2, Cu2S, Cu2O, FeCl2, and Na2S2O4.

[0010] (3) The present invention provides a method for producing a vinyl chloride copolymer as described in (1) or (2), wherein the molar ratio of repeating units in the chain of polyvinyl chloride in the solution to the polymerizable monomer added is 1:1 to 1:3.

[0011] (4) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (3), wherein the polymerizable monomer is one or more selected from the group consisting of C1-12 alkyl (meth)acrylate, styrene, C3-12 cycloalkyl (meth)acrylate, C1-12 sulfoalkyl (meth)acrylate, acrylonitrile, polyoxyethylene (meth)acrylate, poly(ethylene glycol) methyl ether (meth)acrylate, (2-acetoacetoxy)ethyl (meth)acrylate, (meth)acrylamide, N-vinylpyrrolidone, and derivatives thereof.

[0012] (5) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (4), wherein the molar ratio of repeating units in the chain of polyvinyl chloride in the solution to the ligand added is 1000:0.5 to 1000:1.5.

[0013] (6) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (5), wherein the ligand is one or more selected from the group consisting of 2,2'-bipyridine, triphenylphosphine, alkyl-2,2'-bipyridine, 4,4-dinonyl-2,2'-bipyridine, 4,4-diheptyl-2,2'-bipyridine, tris(2-aminoethyl)amine, tris[2-(dimethylamino)ethyl]amine, tris[(2-pyridyl)methyl]amine, N,N,N',N',N''-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetraamine, and tetramethylethylenediamine.

[0014] (7) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (6), wherein the reducing agent is one or more soluble reducing agents selected from the group consisting of Sn(EH)2, ascorbic acid, glucose, and azobisisobutyronitrile.

[0015] (8) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (7), wherein the molar ratio of repeating units in the chain of polyvinyl chloride in the solution to the reducing agent added is 1000:5 to 1000:20.

[0016] (9) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (8), wherein the reducing agent is a metallic solid reducing agent selected from the group consisting of copper, zinc, magnesium, and iron.

[0017] (10) The present invention provides a method for producing a vinyl chloride copolymer according to any one of the above (1) to (9), wherein the solvent of the solution is one or more selected from the group consisting of cyclohexanone, tetrahydrofuran, methyl ethyl ketone, and dimethylformamide.

[0018] (11) In the present invention, the S1 step includes a bubbling step for removing oxygen in the solution, and provides a method for producing a vinyl chloride-based copolymer according to any one of the above (1) to (10).

[0019] (12) In the present invention, the S2 step is carried out at a temperature of 25 to 200 °C for 0.1 to 100 hours, and provides a method for producing a vinyl chloride-based copolymer according to any one of the above (1) to (11).

[0020] (13) In the present invention, the S2 step is carried out until the polymerization conversion rate reaches 50% or more, and provides a method for producing a vinyl chloride-based copolymer according to any one of the above (1) to (12).

[0021] (14) The present invention further includes a step (S3) of cooling and filtering the polymerization reactant, and a step (S4) of drying the filtered vinyl chloride-based copolymer, and provides a method for producing a vinyl chloride-based copolymer according to any one of the above (1) to (13).

[0022] (15) The present invention provides a vinyl chloride-based copolymer that includes units derived from vinyl chloride monomers and units derived from polymerizable monomers. The polymerizable monomers are one or more selected from the group consisting of C1-12 alkyl (meth) acrylates, styrene, C3-12 cycloalkyl (meth) acrylates, C1-12 sulfoalkyl (meth) acrylates, acrylonitrile, polyoxyethylene (meth) acrylates, poly(ethylene glycol) methyl ether (meth) acrylates, (2-acetoacetoxy) ethyl (meth) acrylates, (meth) acrylamides, N-vinylpyrrolidone, and derivatives thereof, and has a glass transition temperature (Tg) of 90 to 120 °C.

Advantages of the Invention

[0023] The vinyl chloride-based copolymer produced by using the production method of the present invention has a higher glass transition temperature than conventional vinyl chloride-based copolymers, and thus can be widely applied to various product fields that require high heat resistance.

Mode for Carrying Out the Invention

[0024] Hereinafter, the present invention will be described in more detail. The terms and words used in this specification and the claims should not be construed as being limited to ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept consistent with the technical idea of the present invention, in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0025] Method for producing vinyl chloride copolymers The present invention relates to a method for producing a vinyl chloride copolymer using conventional ATRP. By optimizing the amount of catalyst introduced based on the number of moles of repeating units in the chain of polyvinyl chloride in solution, a high conversion rate in the polymerization process and excellent thermal stability of the finally produced copolymer can be achieved.

[0026] Specifically, the present invention includes a step (S1) of introducing a reducing agent, a polymerizable monomer, a catalyst, and a ligand into a solution containing polyvinyl chloride, and a step (S2) of heating the solution to perform a polymerization reaction. The molar ratio of the repeating units in the chain of polyvinyl chloride in the solution to the introduced catalyst is 1000:0.3 to 1000:0.6, and a method for producing a vinyl chloride copolymer is provided.

[0027] The present invention forms a vinyl chloride copolymer by further copolymerizing a polymerizable monomer with polyvinyl chloride in a polymerized form, thereby using polyvinyl chloride as one reaction raw material. The polyvinyl chloride used in the present invention preferably has a weight average molecular weight of 30,000 to 100,000 g / mol, and more specifically, those having a weight average molecular weight of 50,000 to 85,000 g / mol may also be used. When polyvinyl chloride having a weight average molecular weight within the above-mentioned range is used, polyvinyl chloride is well dispersed in the solvent, and the polymerizable monomer can be copolymerized uniformly.

[0028] On the other hand, the catalyst introduced in step S1 may be one or more selected from the group consisting of Cu(0), Fe(0), Cu2Te, Cu2Se, CuCl2, Cu2S, Cu2O, FeCl2, and Na2S2O4, and CuCl2 is particularly preferred. The catalysts listed above are catalysts that have the property of effectively donating electrons to polyvinyl chloride and are catalysts used in polymerization reactions using ATRP.

[0029] The present invention is characterized by optimizing the amount of catalyst added based on the amount of repeating units in the polyvinyl chloride chain, thereby improving the physical properties, particularly the heat resistance, of the vinyl chloride copolymer ultimately produced. More specifically, the amount of catalyst added in step S1 may be such that the molar ratio of repeating units in the polyvinyl chloride chain in the solution to the added catalyst is 1000:0.3 to 1000:0.6, preferably 1000:0.4 to 1000:0.6. When the amount of catalyst added is within the aforementioned range, a sufficiently high conversion rate can be obtained, and the heat resistance of the vinyl chloride copolymer ultimately produced can be further improved. On the other hand, the number of moles of repeating units in the polyvinyl chloride chain can be calculated by dividing the molecular weight of the polyvinyl chloride polymer used by the molecular weight of the repeating units, which is equivalent to the degree of polymerization of the polyvinyl chloride used.

[0030] In the method for producing a vinyl chloride copolymer of the present invention, the molar ratio of repeating units in the chain of polyvinyl chloride in the solution to the polymerizable monomer added may be 1:1 to 1:3, preferably 1:1.5 to 1:2.5. If the amount of polymerizable monomer is less than this, the amount of monomer that undergoes polymerization will be relatively small, and a sufficient conversion rate cannot be obtained. If the amount of polymerizable monomer is more than this, the physical properties of some of the copolymers ultimately produced may be inferior.

[0031] The polymerizable monomer is a monomer containing a double bond and usable as a monomer for radical polymerization. More specifically, it may be one or more selected from the group consisting of C1-12 alkyl (meth)acrylate, styrene, C3-12 cycloalkyl (meth)acrylate, C1-12 sulfoalkyl (meth)acrylate, acrylonitrile, polyoxyethylene (meth)acrylate, poly(ethylene glycol) methyl ether (meth)acrylate, (2-acetoacetoxy)ethyl (meth)acrylate, (meth)acrylamide, N-vinylpyrrolidone, and derivatives thereof. Particularly preferably, the polymerizable monomer may be styrene or methyl methacrylate. When the polymerizable monomer described above is further copolymerized with polyvinyl chloride, the final copolymer produced has excellent thermal stability and can maintain the excellent properties of polyvinyl chloride itself.

[0032] In the method for producing a vinyl chloride copolymer of the present invention, the molar ratio of repeating units in the chain of polyvinyl chloride in the solution to the ligand added may be 1000:0.5 to 1000:1.5, and particularly preferably 1000:0.6 to 1000:1.2. The ligand is a component that can be bonded to a metal or metal ion in the catalyst by a coordination bond, and the ligand bonded to the metal component allows the polymerization reaction to be effectively controlled.

[0033] The ligand may be one or more selected from the group consisting of 2,2'-bipyridine, triphenylphosphine, alkyl-2,2'-bipyridine, 4,4-dinonyl-2,2'-bipyridine, 4,4-diheptyl-2,2'-bipyridine, tris(2-aminoethyl)amine, tris[2-(dimethylamino)ethyl]amine, tris[(2-pyridyl)methyl]amine, N,N,N',N',N''-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetraamine, and tetramethylethylenediamine. The ligands listed above readily form coordination bonds with the metal component in the catalyst and facilitate the copolymerization reaction.

[0034] In the method for producing a vinyl chloride copolymer of the present invention, the reducing agent may be one or more soluble reducing agents selected from the group consisting of Sn(EH)2, ascorbic acid, glucose, and azobisisobutyronitrile. In this case, the molar ratio of repeating units in the polyvinyl chloride chain in the solution to the reduced agent added may be 1000:5 to 1000:20, preferably 1000:6 to 1000:12. When the above-mentioned types of soluble reducing agents are used in the above-mentioned ratios, the coupling reaction in which radicals generated during the polymerization reaction bond with each other and terminate the polymerization reaction can be minimized, and the activity of the catalyst added together can be sufficiently increased.

[0035] On the other hand, in addition to the soluble reducing agents described above, the reducing agent may be a metallic solid reducing agent selected from the group consisting of copper, zinc, magnesium, and iron. The metallic solid reducing agent may be used in solid form immersed in the solution, or it may be used in the form of a wire to increase the specific surface area. A metallic solid reducing agent as described above has the advantage of being reusable.

[0036] In the method for producing a vinyl chloride copolymer of the present invention, the solvent of the solution may be one or more selected from the group consisting of cyclohexanone, tetrahydrofuran, methyl ethyl ketone, and dimethylformamide. The solvents listed above have the advantage of being able to dissolve the aforementioned components well and not interfering with the polymerization reaction.

[0037] On the other hand, step S1 may include a bubbling step to remove oxygen from the solution. Since the presence of oxygen in the solution can induce side reactions in the copolymerization process, the solution may be bubbled with nitrogen or an inert gas to minimize the oxygen content.

[0038] Step S2, a polymerization step performed after step S1, may be carried out at a temperature of 25 to 200°C, preferably 80 to 150°C, for 0.1 to 100 hours, preferably 6 to 48 hours. If the temperature in the polymerization step is too low, it may not be possible to supply enough energy necessary for the polymerization reaction, resulting in insufficient conversion. If the temperature in the polymerization step is too high, side reactions may occur due to the high temperature, or problems such as a decrease in the color of the vinyl chloride copolymer produced may occur. If the time in the polymerization step is too short, an insufficient conversion may not be obtained, and if it is too long, there is the disadvantage of high energy consumption required to maintain the reaction.

[0039] The S2 step in which polymerization is carried out may be performed until the polymerization conversion rate reaches 50% or more. When the polymerization reaction is carried out under the conditions described above, the conversion rate of the final copolymer obtained may be 50% or more.

[0040] The method for producing a vinyl chloride copolymer of the present invention may further include, in addition to the S1 and S2 steps described above, a step of cooling and filtering the polymerization reaction product (S3) and a step of drying the filtered vinyl chloride copolymer (S4). By steps S3 and S4, a pure vinyl chloride copolymer free from unreacted monomers and solvents can be obtained. The cooling and drying temperatures in steps S3 and S4 can be appropriately set by those skilled in the art as needed.

[0041] vinyl chloride copolymer The present invention provides a vinyl chloride copolymer produced by the manufacturing method described above. Specifically, the present invention provides a vinyl chloride copolymer comprising units derived from a vinyl chloride monomer and units derived from a polymerizable monomer, wherein the polymerizable monomer is one or more selected from the group consisting of C1-12 alkyl (meth)acrylate, styrene, C3-12 cycloalkyl (meth)acrylate, C1-12 sulfoalkyl (meth)acrylate, acrylonitrile, polyoxyethylene (meth)acrylate, poly(ethylene glycol) methyl ether (meth)acrylate, (2-acetoacetoxy)ethyl (meth)acrylate, (meth)acrylamide, N-vinylpyrrolidone, and derivatives thereof, and having a glass transition temperature (Tg) of 90 to 120°C.

[0042] The vinyl chloride copolymer provided by the present invention has a form in which a polymerizable monomer is further copolymerized with a vinyl chloride polymer, and by optimizing the amount of catalyst added during the reaction process, it has a relatively high glass transition temperature, specifically a glass transition temperature of 90 to 120°C. The vinyl chloride copolymer of the present invention is particularly suitable for use in fields where high heat resistance is required, in addition to fields where conventional PVC has been applied.

[0043] The present invention will be described in more detail below with reference to examples and experimental examples, but the present invention is not limited to these examples and experimental examples. The examples of the present invention may be modified into various different forms, and the scope of the present invention should not be construed as being limited to the examples described later. The examples of the present invention are provided to explain the present invention more specifically to a person with average knowledge in the industry.

[0044] material Polyvinyl chloride with a weight-average molecular weight of 62,500 g / mol was used, and styrene or methyl methacrylate was used as the polymerizable monomer. Sn(EH)2 or copper wire was used as the reducing agent, and CuCl2 was used as the catalyst. Tris[(2-pyridyl)methyl]amine (TPMA) was used as the ligand, and cyclohexanone was used as the solvent.

[0045] Examples and Comparative Examples Approximately 450 g of cyclohexanone solvent was added to a 2 L flask equipped with a reflux condenser, followed by 25 g of polyvinyl chloride, and the mixture was stirred until it dissolved clearly. Then, the reducing agent and polymerizable monomer were added, and nitrogen bubbling was performed for approximately 30 minutes. At this time, a 1 wt% stock solution of the catalyst and ligand was also prepared in the same solvent and nitrogen bubbling was performed. After that, the flask was immersed in an oil bath set to the polymerization temperature, and the catalyst and ligand were added after 30 minutes. The polymerization reaction was then carried out for 24 hours. After polymerization was complete, approximately 200 g of tetrahydrofuran was added, and the reaction product was cooled to room temperature. Then, the reaction product was precipitated using isopropyl alcohol, filtered, and dried in a vacuum drying oven at 30°C for 24 hours to obtain the final product. The types and contents of monomers, catalysts, reducing agents, and ligands used in each example and comparative example, as well as the polymerization temperature, are summarized in Table 1 below.

[0046] [Table 1]

[0047] *MMA: Methyl methacrylate *TPMA: Tris[(2-pyridyl)methyl]amine *PVCru: Number of repeating units in the polyvinyl chloride chain *M: Number of moles of polymerizable monomers *Cat: Number of moles of catalyst *Li: Number of moles of ligand *RA: Moles of reducing agent / Depth of immersion in solution for metallic reducing agents

[0048] On the other hand, in Example 8 of the examples in the table above, recycled PVC was used as the reaction material instead of general PVC, and this PVC also has a weight-average molecular weight of 62,500 g / mol.

[0049] Experimental Example 1: Confirmation of Conversion Rate Before polymerization began and after polymerization was completed, 0.2 g of the polymerization sample was separated and precipitated in 4 g of methanol, and then GC analysis was performed to determine [M]0 and [M] t This was confirmed. Subsequently, the conversion rate was calculated using the following formula. Meanwhile, [M]0 is the amount of the initial monomer, and [M] t This refers to the amount of monomer after the polymerization reaction is complete. Conversion rate = ([M]0 - [M] t ) / [M]0×100% The results are summarized in Table 2 below.

[0050] [Table 2]

[0051] As can be seen from Table 2 above, all of the examples of the present invention achieved a high conversion rate of 50% or more, while the comparative examples showed a low conversion rate of as low as 10%. In particular, Comparative Example 3 used less catalyst than the present invention, and Comparative Example 4 used more catalyst than the present invention. Both Comparative Examples 3 and 4 achieved lower conversion rates than the examples of the present invention, which means that a particularly high conversion rate can be achieved within the range of catalyst usage limited by the present invention.

[0052] Furthermore, Examples 5-8 showed high conversion rates, which was confirmed to be due to the higher reactivity of the monomer MMA used in Examples 5-8 compared to styrene. In Comparative Example 5, gelation occurred during the polymerization process, making it difficult to measure the conversion rate itself. Also, Examples 6 and 7, which reused copper wire, showed surprisingly high conversion rates, confirming that a sufficiently high conversion rate can be obtained even when a metallic reducing agent is reused.

[0053] Experimental Example 2. Confirmation of the glass transition temperature of copolymers. The glass transition temperatures of the copolymers produced in the above examples and comparative examples were confirmed. The glass transition temperatures were determined using DSC analysis, with a TA Instruments DSC2500 analyzer used. The results are summarized in Table 3 below.

[0054] [Table 3]

[0055] As can be seen from Table 3 above, the copolymer produced in the example of the present invention showed a high glass transition temperature of 90°C or higher, while the copolymer produced in the comparative example showed a relatively low glass transition temperature. From this, it can be confirmed that the copolymer produced using the production method of the present invention has high heat resistance and can be applied to various product fields where high heat resistance is required. On the other hand, in the case of Comparative Example 5, as mentioned earlier, the conversion rate could not be measured, and therefore the glass transition temperature could not be accurately measured because gelation occurred during polymerization.

[0056] Experimental Example 3. Confirmation of the occurrence of a coupling reaction. A coupling reaction refers to a situation where a radical generated during a radical polymerization process combines with another radical, preventing further polymerization. The occurrence of a coupling reaction means that the copolymerization process is not proceeding smoothly, and the presence or absence of a coupling reaction can be confirmed by GPC (Geomorphic Spectroscopy). The presence or absence of coupling reactions was also confirmed by GPC for the examples and comparative examples of the present invention, and the results are summarized in Table 4 below. For the GPC analysis, Waters' ALLIANCE E2695 product was used.

[0057] [Table 4]

[0058] As can be seen from Table 4 above, coupling reactions occurred in Comparative Examples 4 and 5, where a larger amount of catalyst was used compared to the present invention. In particular, in Comparative Example 5, where an even larger amount of catalyst was used, the coupling reaction occurred at a very early stage. In Comparative Example 5, because the coupling reaction occurred at an early stage, polymerization did not proceed sufficiently. As a result, as confirmed in Experimental Example 1 above, a gelation phenomenon occurred, and the conversion rate itself could not be measured. This confirms that the amount of catalyst used in the present invention is within a range that can achieve the optimal conversion rate without causing a coupling reaction.

Claims

1. Step (S1) involves adding a reducing agent, polymerizable monomer, catalyst, and ligand to a solution containing polyvinyl chloride, The steps include raising the temperature of the solution to carry out the polymerization reaction (S2), Includes, The molar ratio of repeating units in the polyvinyl chloride chain in the aforementioned solution to the catalyst added is 1000:0.3 to 1000:0.

6. A method for producing a vinyl chloride copolymer, wherein the reducing agent is one or more soluble reducing agents selected from the group consisting of Sn(EH)2, glucose, and azobisisobutyronitrile.

2. The catalyst is Cu(0), Fe(0), Cu ２ Te, Cu ２ Se, CuCl ２ , Cu ２ S, Cu ２ O, FeCl ２ , and Na ２ S ２ O ４ The method for producing a vinyl chloride copolymer according to claim 1, wherein the method is one or more selected from the group consisting of

3. The method for producing a vinyl chloride copolymer according to claim 1, wherein the molar ratio of repeating units in the polyvinyl chloride chain in the solution to the polymerizable monomer added is 1:1 to 1:

3.

4. The method for producing a vinyl chloride copolymer according to claim 1, wherein the polymerizable monomer is one or more selected from the group consisting of C1-12 alkyl (meth)acrylate, styrene, C3-12 cycloalkyl (meth)acrylate, C1-12 sulfoalkyl (meth)acrylate, acrylonitrile, polyoxyethylene (meth)acrylate, poly(ethylene glycol) methyl ether (meth)acrylate, (2-acetoacetoxy)ethyl (meth)acrylate, (meth)acrylamide, N-vinylpyrrolidone, and derivatives thereof.

5. The method for producing a vinyl chloride copolymer according to claim 1, wherein the molar ratio of repeating units in the polyvinyl chloride chain in the solution to the ligand added is 1000:0.5 to 1000:1.

5.

6. The method for producing a vinyl chloride copolymer according to claim 1, wherein the ligand is one or more selected from the group consisting of 2,2'-bipyridine, triphenylphosphine, alkyl-2,2'-bipyridine, 4,4-dinonyl-2,2'-bipyridine, 4,4-dheptyl-2,2'-bipyridine, tris(2-aminoethyl)amine, tris[2-(dimethylamino)ethyl]amine, tris[(2-pyridyl)methyl]amine, N,N,N',N',N''-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetraamine, and tetramethylethylenediamine.

7. The method for producing a vinyl chloride copolymer according to claim 1, wherein the molar ratio of repeating units in the polyvinyl chloride chain in the solution to the reduced agent added is 1000:5 to 1000:

20.

8. The method for producing a vinyl chloride copolymer according to claim 1, wherein the solvent of the solution is one or more selected from the group consisting of cyclohexanone, tetrahydrofuran, methyl ethyl ketone, and dimethylformamide.

9. The method for producing a vinyl chloride copolymer according to claim 1, wherein the S1 step includes a bubbling step for removing oxygen from the solution.

10. The method for producing a vinyl chloride copolymer according to claim 1, wherein step S2 is carried out at a temperature of 25 to 200°C for 0.1 to 100 hours.

11. The method for producing a vinyl chloride copolymer according to claim 1, wherein step S2 is carried out until the polymerization conversion rate is 50% or more.

12. Step (S3) involves cooling and filtering the polymerization reaction product, A method for producing a vinyl chloride copolymer according to claim 1, further comprising the step (S4) of drying the filtered vinyl chloride copolymer.

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