Method for preparing vinyl chloride-based polymer

Abstract

The present invention relates to a method for efficiently preparing a vinyl chloride-based polymer having a high plasticizer absorption rate and an appropriate average particle diameter by using an optimal combination of a first dispersant and a second dispersant and terminating a reaction at an appropriate time.

Description

Method for producing vinyl chloride polymer

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0098673, filed July 28, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a novel method for producing a vinyl chloride polymer, which can efficiently produce unreacted vinyl chloride monomer by increasing the particle porosity of the vinyl chloride polymer produced, and at the same time, can produce a vinyl chloride polymer having excellent processability due to an excellent plasticizer absorption rate of the vinyl chloride polymer.

[0005] Generally, vinyl chloride polymers contain at least 50% vinyl chloride. They are inexpensive, easily adjustable in hardness, and compatible with most processing equipment, offering a wide range of applications. Furthermore, they boast excellent physical and chemical properties, such as mechanical strength, weather resistance, and chemical resistance. These properties make them the most widely used general-purpose resins worldwide for consumer and industrial applications, including films, sheets, and molded products. They are also widely used in diverse fields, including construction materials, household goods, automotive interiors, and decorative materials.

[0006] In particular, vinyl chloride resins are not only used for rigid applications such as pipes and chassis, but are also widely used for soft applications such as films, sheets, and wires by adding various additives including plasticizers. However, since soft vinyl chloride resins essentially contain plasticizers, to be used as soft vinyl chloride resins, the vinyl chloride polymer must have excellent compatibility with the plasticizer and plasticizer absorption performance, and internal pores must be developed within the vinyl chloride polymer.

[0007] In addition, excellent plasticizer absorption performance has the effect of improving the protrusion quality, which is one of the important properties when producing products such as films and sheets.

[0008] Therefore, a technology for manufacturing a vinyl chloride polymer with excellent plasticizer absorption performance and developed internal pores of the polymer is required.

[0009] In general, it is known that in order to manufacture a polymer with excellent plasticizer absorption performance and developed internal pores, it is necessary to increase the content of a secondary dispersant with a low degree of saponification during polymerization, or to introduce the dispersant in a divided or continuous manner. However, excessive use of a secondary dispersant not only reduces particle stability during the polymerization process, which leads to polymerization instability, but also reduces the apparent specific gravity of the manufactured polymer, which reduces processing productivity and makes it difficult to transport for actual use. In addition, the divided or continuous introduction of the dispersant has the disadvantage of requiring additional facility investment, and since particle formation occurs at the early stage, there are restrictions and limitations on improving particle porosity as the dispersant is introduced during the reaction process.

[0010] Research is ongoing on a novel manufacturing method for producing a vinyl chloride polymer that has excellent plasticizer absorption performance and developed internal pores to solve the above problems.

[0011] Meanwhile, in addition to improving plasticizer absorption performance, regulations on reducing volatile organic compounds (VOCs) that can be generated from vinyl chloride polymers are becoming increasingly important in various industrial fields, such as the construction market or the automotive and electronics industries. VOCs are carcinogens that cause nervous system disorders through skin contact or inhalation, and are directly harmful to the human body, such as by causing foul odors. In addition, they are known to be environmentally harmful substances by participating in photochemical reactions in the atmosphere to produce secondary pollutants such as photochemical oxides. Accordingly, countries around the world are implementing regulations on reducing volatile organic compounds. Since unreacted residual vinyl chloride monomers exist as volatile organic compounds in vinyl chloride polymers, improving the recovery efficiency of residual monomers within the manufactured polymer has emerged as a critical issue in the manufacturing process of vinyl chloride polymers.

[0012] Thus, research is required on a process for manufacturing a vinyl chloride polymer that has excellent plasticizer absorption performance, developed internal pores, and superior quality, while also improving the recovery efficiency of unreacted monomers.

[0013] The present invention provides a novel method for producing a vinyl chloride polymer capable of producing a vinyl chloride polymer having a high polymerization degree and being non-toxic.

[0014] In order to solve the above-mentioned problem, the present invention provides a method for producing a novel vinyl chloride polymer.

[0015] Specifically, (1) the present invention provides a method for producing a vinyl chloride polymer, comprising the steps of: (S1) introducing polymerization water, an initiator, a first dispersant, a second dispersant, and a vinyl chloride monomer into a polymerization reactor and initiating a polymerization reaction; and (S2) terminating the polymerization reaction to obtain a vinyl chloride polymer, wherein the first dispersant is polyvinyl alcohol having a degree of hydration of 30 to 64 mol%, the second dispersant is polyvinyl alcohol having a degree of hydration of 70 to 95 mol%, and the weight ratio of the first dispersant to the second dispersant is 3.4 to 12.0, and the first dispersant and the second dispersant are introduced in a total amount of 0.15 to 0.5 parts by weight relative to 100 parts by weight of the vinyl chloride monomer.

[0016] (2) The present invention provides a method for producing a vinyl chloride polymer, wherein the polymerization reaction in (1) above is suspension polymerization.

[0017] (3) The present invention provides a method for producing a vinyl chloride polymer in (1) or (2), wherein the first dispersant is polyvinyl alcohol having a hydration degree of 45 to 60 mol%.

[0018] (4) The present invention provides a method for producing a vinyl chloride polymer, wherein the second dispersant is polyvinyl alcohol having a hydration degree of 75 to 80 mol% in any one of the above (1) to (3).

[0019] (5) The present invention provides a method for producing a vinyl chloride polymer, wherein the weight ratio of the first dispersant to the second dispersant is 5.0 to 9.0 in any one of the above (1) to (4).

[0020] (6) The present invention provides a method for producing a vinyl chloride polymer, wherein the first dispersant and the second dispersant are added in an amount of 0.05 to 0.4 parts by weight based on 100 parts by weight of a vinyl chloride monomer in any one of the above (1) to (5).

[0021] (7) The present invention provides a method for producing a vinyl chloride polymer, wherein in any one of the above (1) to (6), the initiator is at least one selected from the group consisting of a polyacyl peroxide initiator, a peroxydicarbonate initiator, a peroxyester initiator, a sulfate initiator, and an azo initiator.

[0022] (8) The present invention provides a method for producing a vinyl chloride polymer, wherein the initiator is added in an amount of 0.02 to 0.2 parts by weight relative to 100 parts by weight of a vinyl chloride monomer in any one of the above (1) to (7).

[0023] (9) The present invention provides a method for producing a vinyl chloride polymer, wherein the polymerization reaction is performed in the presence of a protective colloid in any one of the above (1) to (8).

[0024] (10) The present invention provides a method for producing a vinyl chloride polymer, wherein the protective colloid is at least one selected from the group consisting of vinyl alcohol resin, cellulose, and unsaturated organic acid polymers, in any one of the above (1) to (9).

[0025] (11) The present invention provides a method for producing a vinyl chloride polymer, wherein the protective colloid is added in an amount of 0.03 to 3.0 parts by weight relative to 100 parts by weight of a vinyl chloride monomer in any one of the above (1) to (10).

[0026] (12) In any one of the above (1) to (11), the S2 step has a polymerization reactor pressure of 4.5 to 6.0 kg / cm 2 A method for producing a vinyl chloride polymer is provided, which comprises adding a reaction terminator at a point where the reaction reaches a predetermined temperature.

[0027] (13) The present invention provides a method for producing a vinyl chloride polymer, wherein the reaction terminator is at least one selected from the group consisting of a phenol compound, an amine compound, a nitrile compound, and a sulfur compound, in any one of the above (1) to (12).

[0028] (14) The present invention provides a method for producing a vinyl chloride polymer, further comprising a step (S3) of dehydrating and drying the obtained vinyl chloride polymer in any one of the above (1) to (13).

[0029] (15) The present invention provides a method for producing a vinyl chloride polymer, wherein the vinyl chloride polymer has a plasticizer absorption rate (CPA) of 38 wt% or more in any one of the above (1) to (14).

[0030] The present invention provides a method for producing a vinyl chloride polymer, which can produce a high-quality vinyl chloride polymer having a high plasticizer absorption rate and particle porosity and thus can be applied to various product fields, while efficiently removing unreacted monomers.

[0031] Hereinafter, the present invention will be described in more detail.

[0032] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0033] Meanwhile, the term "vinyl chloride polymer" used in this specification encompasses a compound produced by polymerizing a vinyl chloride monomer, i.e., a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and a vinyl monomer copolymerizable with the vinyl chloride monomer, and may mean a polymer chain derived from a vinyl chloride monomer.

[0034]

[0035] Method for producing vinyl chloride polymer

[0036] The present invention provides a method for producing a vinyl chloride polymer, comprising the steps of (S1) introducing polymerization water, an initiator, a first dispersant, a second dispersant, and a vinyl chloride monomer into a polymerization reactor and initiating a polymerization reaction, and (S2) terminating the polymerization reaction to obtain a vinyl chloride polymer, wherein the first dispersant is polyvinyl alcohol having a degree of hydration of 30 to 64 mol%, the second dispersant is polyvinyl alcohol having a degree of hydration of 70 to 95 mol%, and the weight ratio of the first dispersant to the second dispersant is 3.4 to 12.0, and the first dispersant and the second dispersant are introduced in a total amount of 0.15 to 0.5 parts by weight relative to 100 parts by weight of the vinyl chloride monomer.

[0037] According to the method for producing a vinyl chloride polymer of the present invention, a vinyl chloride polymer can be produced using existing equipment without separate equipment investment by introducing the entire amount of a dispersant at the beginning of the reaction, and a vinyl chloride polymer having a high particle porosity and plasticizer absorption rate can be produced by optimizing the conditions of the first dispersant and the second dispersant introduced.

[0038]

[0039] Hereinafter, the method for producing a vinyl chloride polymer of the present invention is explained step by step.

[0040]

[0041] Polymerization reaction initiation step (S1)

[0042] The method for producing a vinyl chloride polymer of the present invention includes a step (S1) of introducing polymerization water, an initiator, a first dispersant, a second dispersant, and a vinyl chloride monomer into a polymerization reactor and initiating a polymerization reaction.

[0043] The above step S1 is a step for initiating a polymerization reaction according to a general method for producing a vinyl chloride polymer. In particular, the polymerization method in the method for producing a vinyl chloride polymer of the present invention is suspension polymerization, and the suspension polymerization may be performed in the presence of polymerization water. The polymerization water is a polymerization solvent, and various types of polymerization water such as distilled water or deionized water may be used, and deionized water is preferably used. The temperature of the polymerization water may be appropriately selected in consideration of the temperature at which suspension polymerization takes place, and the amount of the polymerization water may also be appropriately used depending on the polymerization conditions. For example, it may be used in an amount of 70 parts by weight or more, specifically 70 to 300 parts by weight, based on 100 parts by weight of the vinyl chloride monomer.

[0044]

[0045] The above initiator is not particularly limited as long as it is applicable to suspension polymerization of a vinyl chloride monomer, and specifically, the initiator may be at least one selected from the group consisting of a polyacyl peroxide initiator, a peroxydicarbonate initiator, a peroxyester initiator, a sulfate initiator, and an azo initiator.

[0046] More specifically, the diacyl peroxide initiator may be at least one selected from the group consisting of dicumyl peroxide, dipentyl peroxide, 3,3,5-trimethyl hexanoyl peroxide, and dilauryl peroxide. The peroxydicarbonate initiator may be at least one selected from the group consisting of diisopropyl peroxydicarbonate, di-sec-butylperoxydicarbonate, and di-2-ethylhexyl peroxide. The peroxyester initiator may be t-butylperoxypivalate, cumylperoxydecanoate, or t-butylperoxy neodecanoate, or a mixture thereof. The sulfate initiator may be potassium persulfate, ammonium persulfate, or a mixture thereof. The azo initiator may be azobis-2,4-dimethylvaleronitrile.

[0047] The above initiator may be added in an amount of 0.02 to 0.2 parts by weight relative to 100 parts by weight of the vinyl chloride monomer, and preferably 0.04 to 0.12 parts by weight. If the amount of initiator added is too small, the reaction time is delayed, resulting in a decrease in productivity. If the amount of initiator added is too large, the initiator may not be completely consumed during the polymerization process and may remain in the vinyl chloride polymer ultimately produced, which may lower the thermal stability of the resin.

[0048]

[0049] The above dispersant is intended to disperse the vinyl chloride monomer introduced together into the solvent, and different types of first and second dispersants may be used together. More specifically, the first dispersant may be polyvinyl alcohol having a relatively low hydration degree of 30 to 64 mol%, and the second dispersant may be polyvinyl alcohol having a relatively high hydration degree of 70 to 95 mol%. When two types of polyvinyl alcohols having different hydration degrees are mixed and used as a dispersant, the stability of the final particles can be further increased, while basic physical properties such as polymer particle size and plasticizer absorption rate can be easily controlled, and polymer particles having a relatively fast melting point can be obtained while satisfying the basic physical properties required for the product and having a skin layer that is not too thick.

[0050] More preferably, the first dispersant may be polyvinyl alcohol having a hydration degree of 45 to 60 mol%, and the second dispersant may be polyvinyl alcohol having a hydration degree of 75 to 80 mol%. When the hydration degrees of the first dispersant and the second dispersant are within the above-described range, the dispersing effect by the first dispersant and the second dispersant may be particularly excellent. Meanwhile, the polyvinyl alcohol used as a dispersant in this step is in a form in which polyvinyl acetate is hydrated to replace some of the acetate with alcohol, and the hydration degree is defined as the degree to which the acetate is replaced with alcohol.

[0051] Meanwhile, in this step, the weight ratio of the first dispersant to the second dispersant may be 3.4 to 12.0, and preferably 3.4 or more, 3.7 or more, 4.0 or more, 4.5 or more, 4.8 or more, or 5.0 or more, and 12.0 or less, 11.5 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, or 5.5 or less. In the present invention, it may be preferable that the first dispersant having a relatively low hydration degree is added in a large amount compared to the second dispersant. If the content of the first dispersant is excessively large compared to the second dispersant, the stability of the particles may decrease during the polymerization process, a large amount of scale may be generated, and vinyl chloride polymer particles may not be obtained in a consistent shape. Furthermore, the bulk density of the finally manufactured vinyl chloride polymer may be too low, which may cause a problem of a decrease in the extrusion amount. Conversely, if the first dispersant is added in a smaller amount than the second dispersant, the pores inside the obtained vinyl chloride polymer particles may be reduced, resulting in a low plasticizer absorption rate. This may result in the discharge of residual monomers into the atmosphere being difficult, and the content of unreacted monomers remaining in the final product may rapidly increase.

[0052] In this step, the first dispersant and the second dispersant may be added in an amount of 0.15 to 0.5 parts by weight based on 100 parts by weight of the vinyl chloride monomer, and particularly preferably, the first dispersant may be added in an amount of 0.15 to 0.5 parts by weight or more, or 0.155 to 0.5 parts by weight or more and 0.5 to 0.45 parts by weight or less, or 0.4 to 0.4 parts by weight or less based on 100 parts by weight of the vinyl chloride monomer. In addition, the first dispersant may be added in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the vinyl chloride monomer, and the second dispersant may be added in an amount of 0.01 to 0.2 parts by weight based on 100 parts by weight of the vinyl chloride monomer. If the amount of the first dispersant and the second dispersant added is too small, the dispersant itself cannot perform its role sufficiently, which may result in a decrease in polymerization stability. If the amount of dispersant used is too large, the excessively added dispersant component may remain in the vinyl chloride polymer that is ultimately manufactured and act as an impurity, which may adversely affect the product quality.

[0053]

[0054] Meanwhile, the polymerization reaction initiated in the above step S1 may be performed in the presence of a protective colloid. The protective colloid may be at least one selected from the group consisting of vinyl alcohol resin, cellulose, and unsaturated organic acid polymers.

[0055] The vinyl alcohol resin used as the protective colloid may preferably have a hydration degree of 30 to 90 wt% and a viscosity of 10 to 60 cps as a 4% aqueous solution at 15 to 25°C. In addition, the cellulose used as the protective colloid may preferably have a content of hydroxypropyl groups of 3 to 20 wt% and a viscosity of 10 to 20,000 cps as a 2% aqueous solution at 15 to 25°C. In addition, the unsaturated organic acid polymer used as the protective colloid may be at least one selected from the group consisting of acrylic acid polymers, methacrylic acid polymers, itaconic acid polymers, fumaric acid polymers, maleic acid polymers, succinic acid polymers, and gelatin. When a protective colloid satisfying the above-described conditions is used, the stability of the vinyl chloride monomer during the manufacturing process can be further improved.

[0056] The above protective colloid may be added in an amount of 0.03 to 3.0 parts by weight relative to 100 parts by weight of the vinyl chloride monomer, and particularly preferably, 0.05 to 2.0 parts by weight. When the amount of the protective colloid added is within the above-described preferred range, droplet stability increases, so that the breakage and agglomeration of particles are appropriately controlled during the production of the vinyl chloride polymer, and thus, a vinyl chloride polymer including desirable internal voids can be produced.

[0057] In this step, a hydrogen ion concentration regulator may be added to the polymerization reactor as needed. Examples of hydrogen ion concentration regulators that can be used in the present invention include sodium bicarbonate (NaHCO3), sodium borate (Na2B4O7), sodium phosphate dibasic (Na2HPO4), sodium carbonate (Na2CO3), potassium dihydrogen phosphate (KH2PO4), ammonium hydroxide (NH4OH), potassium tartrate (KHC4H4O6), potassium hydrogen phthalate (KHC8H4O4), or calcium hydroxide (Ca(OH)2). These may be used alone or in combination of two or more thereof.

[0058]

[0059] Polymerization reaction progress and termination stage (S2)

[0060] After initiating the polymerization reaction as described above, the polymerization reaction can be continued for a certain period of time under certain temperature conditions and the reaction can be terminated, thereby finally obtaining a vinyl chloride polymer, and accordingly, a step (S2) of proceeding and terminating the polymerization reaction can be performed.

[0061]

[0062] The temperature conditions under which the polymerization reaction is carried out in this step may be 60°C or lower, preferably 55°C or lower, 50°C or lower, or 47°C or lower, and may be 30°C or higher, 35°C or higher, 40°C or higher, or 42°C or higher. In addition, since the polymerization reaction of the vinyl chloride polymer is an exothermic reaction, a heat removal process using a reactor jacket and a reflux condenser (R / CN) may be performed to minimize the temperature change during the polymerization process. When the polymerization reaction is carried out at a temperature in the above range, foam generation can be prevented, while repolymerization and scale formation can be suppressed. In addition, in the above temperature range, decomposition of the polymerization initiator remaining at the end of the reaction is induced, so that a vinyl chloride polymer having better physical properties after the reaction can be manufactured.

[0063] After the polymerization reaction has proceeded for a certain period of time, the reaction can be terminated at a point when the reaction is judged to be sufficiently completed. Termination of the reaction may be performed by introducing a reaction terminator into the polymerization reactor. The reaction terminator can terminate the polymerization reaction by reacting with the remaining unreacted initiator, thereby causing the initiator to lose its function, and may be one or more selected from the group consisting of a phenol compound, an amine compound, a nitrile compound, and a sulfur compound. The above phenol compounds are triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate, hydroquinone, p-methoxy phenol, t-butyl-4-hydroxyanisole, n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, 2,5-di-t-butyl hydroquinone, 4,4'-butylidene bis(3-methyl-6-t-butyl The amine compound may be at least one selected from the group consisting of N,N-diphenyl-p-phenylenediamine and 4,4-bis(dimethylbenzyl)diphenyl.The nitrile compound may be at least one selected from the group consisting of 2-phenyl nitronyl nitroxide, 3-imidazoline nitroxide, and 4-hydroxy-2,2,6,6-tetramethyl piperidine 1-oxyl. The sulfur compound may be at least one selected from the group consisting of dodecyl mercaptan and 1,2-biphenyl-2-thiol. The reaction completion time is when the pressure of the polymerization reactor during the polymerization reaction is 4.5 to 6.0 kg / cm. 2 It may be a point at which the polymerization reactor pressure reaches 4.5 kg / cm, preferably 2 Above, 4.6kg / cm 2 Above, 4.7kg / cm 2 Above, 4.8kg / cm 2 Above, 4.9kg / cm 2 Above, 5.0kg / cm 2 Above, 5.1kg / cm 2 Above, 5.2kg / cm 2 Above, 5.3kg / cm 2 Above, 5.4kg / cm 2 or more than 5.5 kg / cm 2 Above 6.0 kg / cm 2 Below, 5.9kg / cm 2 Less than or equal to 5.8 kg / cm 2 This may be the case. If the reaction termination time is earlier than this, a sufficient conversion rate cannot be obtained, and if the reaction termination time is later than this, the conversion rate is substantially the same, but the energy consumption used to operate the reaction process increases, which may reduce the economic feasibility of the manufacturing process.

[0064]

[0065] In the method for producing a vinyl chloride polymer of the present invention, additives such as antioxidants, bases, crosslinking agents, polymerization regulators, chain transfer agents, antistatic agents, scale inhibitors, and surfactants may be additionally added. The types and contents of the additives are not particularly limited, and any conventional types and contents known in the art may be used. The additives may be added at any point during the polymerization process, and may be added all at once or continuously.

[0066]

[0067] Dehydration and drying stage (S3)

[0068] The method for producing a vinyl chloride polymer of the present invention may further include a step (S3) of dehydrating and drying the vinyl chloride polymer obtained through the preceding step. The vinyl chloride polymer obtained through the preceding step may be obtained in the form of a slurry in which vinyl chloride polymer particles, unreacted monomer, and polymerization water are mixed, and through the dehydration and drying process, only the vinyl chloride polymer can be selectively recovered.

[0069] The dehydration and drying methods in this step are not particularly limited, and any known dehydration and drying method for the production of vinyl chloride polymers can be applied without particular limitation. For example, the final vinyl chloride polymer can be obtained by first dehydrating using equipment such as a centrifuge, and then secondarily drying using equipment such as a fluidized bed dryer. The vinyl chloride polymer obtained after the dehydration and drying steps may be in the form of beads.

[0070]

[0071] The plasticizer absorption rate (CPA) of the vinyl chloride polymer manufactured through the method for manufacturing a vinyl chloride polymer of the present invention described above may be 40 wt% or more, preferably 41 wt% or more, 42 wt% or more, 43 wt% or more, 44 wt% or more, or 45 wt% or more, and may be 60 wt% or less, 59 wt% or less, 58 wt% or less, or 57 wt% or less. The vinyl chloride polymer manufactured through the method for manufacturing the present invention has a high internal porosity and can absorb a large amount of plasticizer, thereby providing excellent processability.

[0072]

[0073] Hereinafter, preferred examples are presented to aid understanding of the present invention. However, the following examples are intended only to illustrate the present invention and are not intended to limit its scope.

[0074]

[0075] Examples and Comparative Examples

[0076] Internal volume 1 m with reflux condenser and stirrer attached 3 390 kg of deionized water was charged into a stainless steel polymerization reactor, and polyvinyl alcohol having a hydration degree of 53 mol% as a first dispersant, polyvinyl alcohol having a hydration degree of 78.5 mol% as a second dispersant, and 30 g of hydroxypropyl methyl cellulose as a protective colloid were charged in batches. After that, 300 kg of vinyl chloride monomer was charged, and 240 g of a 75 wt% solution of t-butyl peroxy neodecanoate, which is an organic peroxide initiator composition, was charged as an initiator.

[0077] Thereafter, the polymerization reaction temperature was maintained at 45°C while the reaction was carried out, and when the pressure of the polymerization reactor reached a certain value, 15 g of 4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl and 60 g of triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate were added as reaction terminators to terminate the reaction. Subsequently, the unreacted monomer and polymer slurry were separated and recovered from the reactor, and the polymer slurry was dehydrated and dried in a fluidized bed dryer to obtain a vinyl chloride polymer in the form of beads.

[0078]

[0079] The input amounts of the first dispersant and the second dispersant used in each example and comparative example, the weight ratio of the input of the first dispersant to the second dispersant, the total input amounts of the first dispersant and the second dispersant relative to 100 parts by weight of the vinyl chloride monomer, and the pressure of the polymerization reactor at the end of the reaction are summarized in Table 1 below.

[0080] Dispersant 1 (g) Dispersant 2 (g) Dispersant 1 / Dispersant 2 Dispersant 1 + Dispersant 2 End pressure (kg / cm) 2 )Embodiment 1450905.00.185.75Embodiment 2480965.00.1925.75Embodiment 35101025.00.2045.75Embodiment 43601053.430.1555.75Embodiment 5360904.00.155.75Embodiment 66001504.00.255.75Embodiment 7675759.00.255.75Embodiment 86906011.50.255.75Embodiment 99001506.00.355.75Embodiment 1012302465.00.4925.75Embodiment 11450905.00.185.90 Example 12450905.00.186.00 Comparative Example 14502851.580.2455.75 Comparative Example 22852851.00.195.75 Comparative Example 3285843.390.1235.75 Comparative Example 41801351.330.1055.75 Comparative Example 513771539.00.515.75

[0081] Experimental Example 1. Measurement of the average particle size of manufactured vinyl chloride polymers.

[0082] The average particle diameter of the bead-shaped vinyl chloride polymers manufactured in the above examples and comparative examples was measured. More specifically, the average particle diameter was measured using a HELOS particle size analyzer according to ISO 13320. The results are summarized in Table 2 below.

[0083] Average particle size (D50, ㎛) Example 1142 Example 2141 Example 3140 Example 4148 Example 5147 Example 6137 Example 7127 Example 8122 Example 9123 Example 10115 Example 11142 Example 12142 Comparative Example 1142 Comparative Example 2149 Comparative Example 3151 Comparative Example 4157 Comparative Example 5101

[0084] As can be seen in Table 2 above, the vinyl chloride polymer manufactured using the manufacturing method of the present invention exhibited an average particle diameter above a certain range, confirming that vinyl chloride polymer beads of an appropriate size can be manufactured using the manufacturing method of the present invention. Meanwhile, in the case of Comparative Example 5, where the first and second dispersants were excessively added, a vinyl chloride polymer having a small particle size was manufactured due to the excessive addition of the dispersant. A decrease in the particle diameter of the vinyl chloride polymer means an increase in the proportion of fine particles, which may increase the fine particles generated during the processing, thereby reducing workability.

[0085]

[0086] Experimental Example 2. Measurement of plasticizer absorption rate

[0087] The plasticizer absorption rates of the vinyl chloride polymers manufactured in the above examples and comparative examples were measured. Measurements were performed using a centrifuge (Continent 512R, Hanil Corporation) based on the ASTM D3367 measurement method. The results are summarized in Table 3 below.

[0088] Plasticizer absorption rate (CPA, wt%) Example 145.5 Example 245.5 Example 345.6 Example 442.8 Example 543.8 Example 643.9 Example 752.4 Example 856.7 Example 947.5 Example 1046.0 Example 1146.2 Example 1246.6 Comparative Example 136.8 Comparative Example 237.8 Comparative Example 338.9 Comparative Example 432.7 Comparative Example 548.2

[0089] As can be seen from Table 3 above, the vinyl chloride polymer manufactured through the manufacturing method of the present invention exhibited a high plasticizer absorption rate of 40 wt% or more. On the other hand, in Comparative Examples 1 to 4, where the ratio of the first dispersant to the second dispersant was lower than that of the present invention, the first dispersant did not work sufficiently, resulting in the manufacture of polymers with significantly reduced plasticizer absorption rates. From this, it was confirmed that the manufacturing method of the present invention can efficiently manufacture vinyl chloride polymers that can be used in various fields requiring high plasticizer absorption rates.

[0090]

[0091] Experimental Example 3. Measurement of the amount of recovered vinyl chloride monomer.

[0092] The amount of unreacted vinyl chloride monomer recovered was measured using a flow meter by depressurizing the polymerized slurry. The results are summarized in Table 4 below.

[0093] Weight of vinyl chloride monomer recovered (kg) Example 149.6 Example 249.6 Example 349.6 Example 449.8 Example 549.2 Example 648.9 Example 748.4 Example 847.9 Example 947.9 Example 1049.2 Example 1149.1 Example 1248.8 Comparative Example 134.6 Comparative Example 235.7 Comparative Example 341.9 Comparative Example 435.3 Comparative Example 544.6

[0094] From the above results, it can be seen that the vinyl chloride polymer manufactured using the method for manufacturing a vinyl chloride polymer of the present invention can quickly recover unreacted vinyl chloride monomer due to its high plasticizer absorption rate, whereas the vinyl chloride polymer manufactured using the manufacturing methods of Comparative Examples 1 to 4 has a low plasticizer absorption amount, so the weight of the recovered vinyl chloride monomer is low and the unreacted vinyl chloride monomer is not well recovered.

Claims

1. Step (S1) of introducing polymerization water, initiator, first dispersant, second dispersant, and vinyl chloride monomer into a polymerization reactor and initiating a polymerization reaction; and It includes a step (S2) of obtaining a vinyl chloride polymer by terminating the polymerization reaction; The above first dispersant is polyvinyl alcohol having a hydration degree of 30 to 64 mol%. The second dispersant is polyvinyl alcohol having a hydration degree of 70 to 95 mol%, The weight ratio of the first dispersant to the second dispersant is 3.4 to 12.0, A method for producing a vinyl chloride polymer, wherein the first dispersant and the second dispersant are added in a total amount of 0.15 to 0.5 parts by weight relative to 100 parts by weight of a vinyl chloride monomer.

2. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the above polymerization reaction is suspension polymerization.

3. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the first dispersant is polyvinyl alcohol having a hydration degree of 45 to 60 mol%.

4. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the second dispersant is polyvinyl alcohol having a hydration degree of 75 to 80 mol%.

5. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the weight ratio of the first dispersant to the second dispersant is 5.0 to 9.

0.

6. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the first dispersant and the second dispersant are added in a total amount of 0.15 to 0.4 parts by weight relative to 100 parts by weight of a vinyl chloride monomer.

7. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the above initiator is at least one selected from the group consisting of a polyacyl peroxide initiator, a peroxydicarbonate initiator, a peroxyester initiator, a sulfate initiator, and an azo initiator.

8. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the above initiator is added in an amount of 0.02 to 0.2 parts by weight relative to 100 parts by weight of a vinyl chloride monomer.

9. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the above polymerization reaction is performed in the presence of a protective colloid.

10. In paragraph 9, A method for producing a vinyl chloride polymer, wherein the above protective colloid is at least one selected from the group consisting of vinyl alcohol resin, cellulose, and unsaturated organic acid polymers.

11. In paragraph 9, A method for producing a vinyl chloride polymer, wherein the above protective colloid is added in an amount of 0.03 to 3.0 parts by weight relative to 100 parts by weight of a vinyl chloride monomer.

12. In paragraph 1, The above S2 step is a polymerization reactor pressure of 4.5 to 6.0 kg / cm 2 A method for producing a vinyl chloride polymer, wherein a reaction terminator is added at a point where the reaction reaches a certain temperature.

13. In paragraph 12, A method for producing a vinyl chloride polymer, wherein the above reaction terminator is at least one selected from the group consisting of a phenol compound, an amine compound, a nitrile compound, and a sulfur compound.

14. In paragraph 1, A method for producing a vinyl chloride polymer, further comprising a step (S3) of dehydrating and drying the obtained vinyl chloride polymer.

15. In paragraph 1, A method for producing a vinyl chloride polymer, wherein the plasticizer absorption rate (CPA) of the vinyl chloride polymer is 40 wt% or more.