阅读说明：本技术 氯乙烯类聚合物的制备方法 (Process for producing vinyl chloride polymer ) 是由 朴宰贤 李贤珉 河玄圭 金健地 李光珍 全亮俊 朱镇爀 于 2019-10-30 设计创作，主要内容包括：本发明涉及一种氯乙烯类聚合物的制备方法,其中,本发明可以提供一种能够制备氯乙烯类聚合物的方法,在该方法中,通过一起加入碳酸盐类金属盐和过渡金属催化剂,但是控制过渡金属催化剂的加入时间和加入量,生产率优异,同时减少挥发性有机化合物的产生量以适用于环保材料,并且包含制备的聚合物的增塑溶胶的发泡和粘度性能得到改善。(The present invention relates to a method for preparing a vinyl chloride-based polymer, wherein the present invention can provide a method capable of preparing a vinyl chloride-based polymer, in which productivity is excellent while reducing the generation amount of volatile organic compounds to be suitable for an environmentally friendly material by adding a carbonate-based metal salt and a transition metal catalyst together, but controlling the addition time and the addition amount of the transition metal catalyst, and foaming and viscosity properties of a plastisol including the prepared polymer are improved.)

1. A method for producing a vinyl chloride-based polymer, comprising:

vinyl chloride-based monomers are polymerized by adding a carbonate-based metal salt in the presence of one or more emulsifiers and a polymerization initiator,

wherein, at the time of polymerization, when the polymerization conversion rate is in the range of 5% to 35%, a transition metal catalyst is added, and

the transition metal catalyst is added in an amount of 0.01 to 7.5ppm based on the weight of the vinyl chloride-based monomer.

2. The method of claim 1, wherein the metal carbonate salt comprises a metal salt selected from sodium carbonate (Na)₂CO₃) Sodium bicarbonate (NaHCO)₃) Magnesium carbonate (MgCO)₃) Calcium carbonate (CaCO)₃) And potassium carbonate (K)₂CO₃) At least one of (1).

3. The preparation method of claim 1, wherein the transition metal catalyst is added when a polymerization conversion rate is in a range of 10 to 30%.

4. The production method according to claim 1, wherein the transition metal catalyst is added by a batch addition method.

5. The production method according to claim 1, wherein the transition metal catalyst is added in an amount of 0.03ppm to 6.0 ppm.

6. The production method according to claim 1, wherein the transition metal catalyst includes at least one selected from copper sulfate and iron sulfate.

7. The production method according to claim 1, wherein the carbonate-based metal salt is added in an amount of 100ppm to 1,500ppm based on the weight of the vinyl chloride-based monomer.

8. The production method according to claim 1, wherein the polymerization is performed by an emulsion polymerization method.

9. The production method according to claim 1, wherein an oxidizing agent and a reducing agent are not added in the polymerization.

Technical Field

Cross Reference to Related Applications

This application claims the benefit of korean patent application No. 10-2018-.

Technical Field

The present invention relates to a method for producing a vinyl chloride-based polymer, which improves productivity, reduces the amount of volatile organic compounds produced, and improves the viscosity and foaming properties of a plastisol containing the produced polymer.

Background

The vinyl chloride-based polymer is a polymer containing 50% by weight or more of a repeating unit derived from Vinyl Chloride Monomer (VCM), and among them, has various applications because it is inexpensive, easy to control hardness, and applicable to most processing equipment. In addition, since vinyl chloride-based polymers can provide molded articles having excellent physical and chemical properties, such as mechanical strength, weather resistance and chemical resistance, the vinyl chloride-based polymers are widely used in many fields.

Vinyl chloride-based resins are general-purpose resins most widely used as living and industrial materials in the world, and among them, in general, a linear vinyl chloride-based resin (a straight vinyl chloride-based resin) is prepared by a suspension polymerization method as powder particles having a size of about 100 to 200 μm, and a paste vinyl chloride-based resin (a paste vinyl chloride-based resin) is prepared by an emulsion polymerization method as powder particles having a size of about 0.1 to 2 μm.

With respect to a paste-type vinyl chloride-based resin, a latex obtained by emulsion polymerization is generally dried by a spray drying method to form final resin particles, and these particles are dispersed in a solvent or a plasticizer, and used in products such as flooring materials, wall papers, tarpaulins, raincoats, gloves, automobile undercoats, and carpet tiles by processes such as coating (reverse roll coating, knife coating, screen coating, spray coating), gravure and screen printing, spin casting, and case casting and dipping.

In particular, with the recent increase in interest in environmentally friendly products having a small amount of Total Volatile Organic Compounds (TVOCs), many efforts have been made to minimize the content of TVOCs in various product groups produced by many companies, and the demand for products emphasizing environmental protection is increasing.

Therefore, a great deal of research has been conducted to reduce volatile organic compounds generated in molded articles produced using vinyl chloride-based polymers, and research has been conducted on various additives and plasticizers mainly used as auxiliary raw materials.

However, as various regulations on the environment are increasing, replacing plasticizers used as auxiliary raw materials has a limitation in reducing the generation level of volatile organic compounds below an appropriate level. Therefore, there is a need for a method capable of reducing volatile organic compounds generated from the vinyl chloride-based polymer itself while maintaining effective physical properties of the vinyl chloride-based polymer, but since reactivity is lowered and reaction time is increased in the conventional polymerization method, there is a limitation in using the method in a practical place.

[ Prior art documents ]

[ patent document ]

(patent document 1) Korean patent application laid-open No.10-2016-

Disclosure of Invention

Technical problem

The present invention aims to provide a method capable of producing a vinyl chloride-based polymer, in which productivity is excellent while reducing the generation amount of volatile organic compounds to be suitable for an environmentally friendly material by adding a carbonate-based metal salt and a transition metal catalyst together, but controlling the addition time and the addition amount of the transition metal catalyst, and foaming and viscosity properties of a plastisol including the produced polymer are improved.

Technical scheme

According to an aspect of the present invention, there is provided a method for producing a vinyl chloride-based polymer, the method comprising: polymerizing the vinyl chloride-based monomer by adding a carbonate-based metal salt in the presence of one or more emulsifiers and a polymerization initiator, wherein, at the time of polymerization, a transition metal catalyst is added when the polymerization conversion rate is in the range of 5 to 35%, and the amount of the added transition metal catalyst is 0.01 to 7.5ppm based on the weight of the vinyl chloride-based monomer.

Advantageous effects

In the present invention, since the polymerization reaction rate is increased by adding the carbonate-based metal salt and the transition metal catalyst together, but by controlling the addition time and the addition amount of the transition metal catalyst, the generation amount of volatile organic compounds is reduced while securing a high level of productivity, whereby it is possible to prepare a vinyl chloride-based polymer suitable for an eco-friendly material and a vinyl chloride-based polymer having foaming and viscosity properties which are not deteriorated and are equal to or superior to those of conventional polymers to which no metal catalyst is added when they are processed into plastisols.

Detailed Description

Hereinafter, the present invention will be described in more detail to allow the present invention to be more clearly understood.

It will be understood that the words or terms used in the specification and claims should not be construed as meaning defined in commonly used dictionaries. It is also to be understood that the words or terms should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the technical spirit of the present invention, based on the principle that the inventor can appropriately define the meaning of the words or terms to best explain the present invention.

Definition of terms

The term "polymer" as used in this specification refers to a polymeric compound prepared by polymerizing monomers, whether the monomers are of the same or different species. Thus, the generic term "polymer" refers to a polymer prepared from only one type of monomer, including the commonly used term homopolymer and the term copolymer as defined below.

The expression "vinyl chloride-based polymer" used herein inclusively means a compound formed by polymerizing a vinyl chloride-based monomer, and among them, may mean a polymer chain derived from a vinyl chloride-based monomer.

The term "plastisol" used in the present specification means a mixture in which a resin and a plasticizer are mixed so that the mixture can be formed into a continuous film by heating, molding, casting or processing, and, for example, may mean a paste form in which a vinyl chloride-based polymer and a plasticizer are mixed.

The term "composition" as used in this specification includes mixtures of materials comprising the respective components and reaction and decomposition products formed from the materials of the respective components.

In the present specification, the average particle diameter (D)₅₀) Can be defined as a particle size corresponding to 50% of the cumulative number of particles in the particle size distribution curve of the particles. For example, average particle diameter (D)₅₀) Can be measured by using a laser diffraction method. Laser diffraction methods can generally measure particle sizes ranging from submicron to several millimeters, and can yield highly reproducible and high resolution results.

1. Process for producing vinyl chloride polymer

An embodiment of the present invention provides a method for producing a vinyl chloride-based polymer, comprising a step of polymerizing a vinyl chloride-based monomer by adding a carbonate-based metal salt in the presence of one or more emulsifiers and a polymerization initiator, wherein, in the polymerization step, a transition metal catalyst is added when a polymerization conversion rate is in the range of 5% to 35%, and the amount of the added transition metal catalyst is 0.01ppm to 7.5ppm based on the weight of the vinyl chloride-based monomer.

In general, in the process of producing a vinyl chloride-based polymer, sulfonate-based emulsifiers and sulfate-based emulsifiers are most widely used, and it is known that sulfate-based emulsifiers particularly generate a large amount of volatile organic compounds. In addition, the polymerization initiator and the selectively added metal catalyst component, which need to be used in the preparation process, can also increase the amount of volatile organic compounds produced. Therefore, for vinyl chloride polymers themselves, particularly vinyl chloride polymers prepared by using sulfate-based emulsifiers, a technique for reducing volatile organic compounds generated is required, but there is a limitation in commercially widespread use of volatile organic compound reducing agents due to a significant difference in productivity when using the volatile organic compound reducing agents.

That is, the volatile organic compound is reduced by adding a substance generally used as a reducing agent for the volatile organic compound at the initial stage of the reaction and changing the conditions in the reactor, but in this case, the polymerization productivity may be significantly reduced due to the reaction time delay. In particular, in the case of using a strong alkali sodium hydroxide (NaOH), not only polymerization productivity is lowered, but also formation of a vinyl chloride-based polymer for plastisol processing is difficult due to a blocking phenomenon, and in the case of foam preparation by plastisol processing, there is a risk of excessive foaming, and there is almost no effect of reducing volatile organic compounds.

Therefore, as a method for producing a vinyl chloride-based polymer which provides a vinyl chloride-based polymer having less generation of volatile organic compounds and excellent viscosity and foaming properties while remarkably improving productivity, a method for producing a vinyl chloride-based polymer using a carbonate-based metal salt is proposed.

In addition, since carbonate ions are not present in a substance other than a carbonate metal salt, such as sodium hydroxide, the substance can only serve as a pH adjuster and cannot serve as an oxidizing agent and/or a reducing agent, and thus, in the case of using sodium hydroxide to improve productivity using a redox polymerization (redox polymerization) system, there is a limitation in that other auxiliary raw materials, such as an oxidizing agent and/or a reducing agent, which can maintain the redox system by oxidizing and/or reducing transition metal ions, must be included.

In this case, the oxidizing agent and/or the reducing agent mainly used in the vinyl chloride-based polymerization process may be a weak acid substance, and if an excessive amount of the weak acid substance is added to sufficiently oxidize or reduce the metal ion, the polymerization is performed under acidic conditions due to a decrease in pH during the polymerization process, whereby the decomposition reaction of the initiator having higher reactivity under low pH conditions is excessive, resulting in a problem of runaway of the polymerization reaction and a problem of an increase in the amount of volatile organic compounds in the produced polymer. In the case of producing a polymer under acidic conditions, as the number of defective sites in the produced polymer increases, there may arise a problem that the heat resistance of the polymer itself is significantly deteriorated.

Further, in the case of using an acidic substance such as potassium phosphate as a pH adjuster, since the pH of the polymerization reaction is further lowered, the polymerization reaction also proceeds under acidic conditions, and the same problems that occur when an oxidizing agent and/or a reducing agent are added as described above may occur.

However, in the case where a carbonate-based metal salt is added as in the embodiment of the present invention, the carbonate-based metal salt can also serve as a reducing agent due to the carbonate ion to reduce the metal ion, and there is an advantage in that it is not necessary to use an auxiliary raw material such as a separate reducing agent, and the problems caused by the use of the above-mentioned auxiliary raw material can be avoided.

Since carbonate metal salts contain carbonate ions, they must be included in conventional redox polymerization systemsThe acid reducing agent of (1) may not be contained, or may be contained in a trace amount, and since the reduction reaction with the metal ion of the transition metal catalyst proceeds smoothly, the amount of the transition metal catalyst may be significantly reduced, and accordingly, deterioration of physical properties, such as viscosity increase and foam color deterioration, which may occur due to the inclusion of a large amount of the transition metal catalyst, may be prevented. In addition, CO due to carbonate ions generated by reduction reaction of metal ions₃ ^-The residue can decompose the polymerization initiator, further increasing the activity of the polymerization initiator, and also can exert the function of supplying electrons to the structural defects of the vinyl chloride polymer produced, and therefore, the residue has the effect of improving the structural defects of the polymer, and thus, the reactivity, the viscosity of the plastisol, and the foaming performance can be simultaneously improved.

In other words, according to one embodiment of the present invention, it is advantageous that productivity can be remarkably improved without adding an oxidizing agent and/or a reducing agent by using a carbonate metalloid salt (pH adjuster) and a transition metal catalyst even when a redox polymerization system is applied, unlike the conventional case.

In this case, since the transition metal catalyst used together with the carbonate-based metal salt applied to the redox polymerization system as a pH adjuster affects the polymerization reactivity of the monomer and thus affects the formation of the polymer as a whole, for example, promotes the formation of fine particles, it is necessary to appropriately control the formulation properties of the plastisol and the physical properties of the polymer by controlling the addition conditions of the transition metal catalyst.

As described above, the carbonate metal salt is a substance capable of reducing the amount of volatile organic compounds that may be generated from the vinyl chloride polymer itself, wherein the transition metal catalyst is added together to improve reactivity while the carbonate metal salt is added during polymerization, but the addition time and amount of the transition metal catalyst may be controlled to significantly reduce the amount of volatile organic compounds generated, while it is expected that the polymerization productivity is significantly improved, and auxiliary raw materials such as a separate reducing agent are not required even though the redox polymerization system is applied, having the effect of improving viscosity and foaming properties when processed into a plastisol.

Hereinafter, a preparation method according to an embodiment of the present invention will be described in detail.

The method for producing a vinyl chloride-based polymer according to an embodiment of the present invention includes a step of polymerizing a vinyl chloride-based monomer by adding a carbonate-based metal salt in the presence of one or more emulsifiers and a polymerization initiator, wherein this is a step of forming a vinyl chloride-based polymer from a vinyl chloride-based monomer by initiating a polymerization reaction in a reactor.

Specifically, the polymerization according to one embodiment of the present invention may be performed by adding a carbonate metal salt and a vinyl chloride-based monomer to a polymerization reactor filled with polymerization water, a first emulsifier and a polymerization initiator and performing a polymerization reaction. In addition, in the present invention, a second emulsifier may be further added according to need, and the second emulsifier may be continuously added during the polymerization reaction.

Here, the polymerization may be preferably carried out by an emulsion polymerization method, more preferably by a pure emulsion polymerization method.

The polymerization reactor filled with polymerization water, a first emulsifier, and a polymerization initiator may mean a polymerization reactor containing a mixed solution containing polymerization water, a first emulsifier, and a polymerization initiator, and the mixed solution may further contain a dispersant, a chain transfer agent, an electrolyte, and a reaction inhibitor in addition to the polymerization water, the first emulsifier, and the polymerization initiator, but the present invention is not limited thereto.

The polymerization initiator may be used in an amount of 0.01 to 2.0 parts by weight, based on 100 parts by weight of the vinyl chloride-based monomer. The polymerization initiator is not particularly limited, but, for example, may include at least one selected from the group consisting of peroxycarbonates, peroxyesters, and azo-based compounds. Specifically, as for the polymerization initiator, Lauryl Peroxide (LPO), di-2-ethylhexyl peroxydicarbonate (OPP), diisopropyl peroxydicarbonate, tert-butyl peroxypivalate, tert-butyl peroxyneodecanoate, and 2, 2-azobisisobutyronitrile may be used alone or as a mixture of two or more of them.

In addition, the polymerization initiator may be a water-soluble initiator. In the case where the polymerization initiator is a water-soluble initiator, the polymerization initiator is not particularly limited, but, for example, the polymerization initiator may include at least one selected from the group consisting of potassium persulfate, ammonium persulfate, and hydrogen peroxide, and the water-soluble initiator may be preferably used as the polymerization initiator of the present invention, and in particular, potassium persulfate may be used.

Further, the polymerization water may be used in an amount of 70 parts by weight to 200 parts by weight, and the polymerization water may be deionized water, based on 100 parts by weight of the vinyl chloride-based monomer.

In addition, the first emulsifier may be used in an amount of 0.005 to 0.4 parts by weight, for example, 0.01 to 0.4 parts by weight, based on 100 parts by weight of the vinyl chloride-based monomer, the second emulsifier may be continuously added during the reaction after initiation of polymerization, as needed, and may be used in an amount of 1 to 15 parts by weight, based on 100 parts by weight of the vinyl chloride-based monomer.

In the present invention, the first emulsifier and the second emulsifier may be different substances from each other, or may be the same substance, and in the case where the first emulsifier and the second emulsifier are the same substance, the expressions "first" and "second" may be used to distinguish the addition order of the emulsifiers.

Specifically, each of the first and second emulsifiers may be at least one selected from the group consisting of sodium lauryl sulfate, dodecylbenzene sulfonic acid, alpha-olefin sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl ethoxylated sulfate, sodium stearyl sulfate, sodium lauryl ether sulfate, and linear alkylbenzene sulfonate, and the first and second emulsifiers may preferably include sodium lauryl sulfate.

Further, the reaction inhibitor is not particularly limited, but, for example, p-benzoquinone, hydroquinone, butylated hydroxytoluene, monomethyl ether hydroquinone, quaternary butyl catechol, diphenylamine, triisopropanolamine and triethanolamine may be used, and the dispersant is not particularly limited, but, for example, higher alcohols such as lauryl alcohol, myristyl alcohol and stearyl alcohol, or higher fatty acids such as lauric acid, myristic acid, palmitic acid and stearic acid may be used.

In addition, the chain transfer agent is not particularly limited, but, for example, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan and tert-dodecyl mercaptan may be included, and the electrolyte is not particularly limited, but, for example, at least one selected from the group consisting of potassium chloride, sodium chloride, potassium bicarbonate, sodium carbonate, potassium bisulfite, sodium bisulfite, potassium pyrophosphate, tetrasodium pyrophosphate, tripotassium phosphate, trisodium phosphate, dipotassium hydrogen phosphate and disodium hydrogen phosphate may be included.

Further, the vinyl chloride-based monomer according to an embodiment of the present invention may refer to a vinyl chloride-based monomer alone or a mixture of a vinyl chloride-based monomer and a vinyl-based monomer copolymerizable with the vinyl chloride-based monomer. That is, the vinyl chloride-based polymer according to one embodiment of the present invention may be a homopolymer of vinyl chloride or may be a copolymer of a vinyl chloride monomer and an ethylene-based monomer copolymerizable therewith. When the vinyl chloride-based polymer is a copolymer, the content of vinyl chloride may be 50% or more.

Accordingly, the vinyl chloride-based monomer that may be used according to an embodiment of the present invention may be vinyl chloride single species; or may be a mixture of vinyl chloride and a vinyl monomer copolymerizable with vinyl chloride. The ethylenic monomer is not particularly limited, but may include olefinic compounds such as ethylene, propylene and butene; vinyl esters such as vinyl acetate, vinyl propionate, and vinyl stearate; unsaturated nitriles such as acrylonitrile; vinyl alkyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl octyl ether and vinyl lauryl ether; vinyl halides such as vinylidene chloride; unsaturated fatty acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, and itaconic anhydride, and anhydrides of these fatty acids; unsaturated fatty acid esters such as methyl acrylate, ethyl acrylate, monomethyl maleate, dimethyl maleate and butyl benzyl maleate; and a crosslinkable monomer such as diallyl phthalate, and any one thereof or a mixture of two or more thereof may be used.

In addition, according to an embodiment of the present invention, before the polymerization reaction of the present invention is initiated, a mixed solution of polymerization water, a polymerization initiator, a first emulsifier, and a vinyl chloride-based monomer filled in a polymerization reactor may be homogenized, if necessary. Homogenization may be performed by using a homogenizer at a temperature of 30 ℃ or less, particularly at a temperature of 5 ℃ to 25 ℃ for 1 hour to 3 hours. In this case, the homogenizer is not particularly limited, but a conventional homogenizer known in the art may be used, for example, a rotor-stator type homogenizer may be used.

According to an embodiment of the present invention, the carbonate-based metal salt may be added in an amount of 100ppm to 1,500ppm, for example, 600ppm to 1,000ppm, based on the total weight of the vinyl chloride-based monomer. In the case of adding the carbonate-based metal salt in an amount within the above range, when the carbonate-based metal salt is used together with an appropriate amount of the metal catalyst, the effect of improving reactivity can be maximized, while the generation amount of the volatile organic compound can be remarkably reduced.

According to an embodiment of the present invention, the carbonate-based metal salt is not particularly limited as long as it contains carbonate ion (CO)₃ ^2-) That is, however, the carbonate-based metal salt may preferably include one selected from sodium carbonate (Na) in terms of improvement of reactivity₂CO₃) Sodium bicarbonate (NaHCO)₃) Magnesium carbonate (MgCO)₃) Calcium carbonate (CaCO)₃) And potassium carbonate (K)₂CO₃) And more preferably, may include sodium carbonate, sodium bicarbonate, potassium carbonate, or a mixture thereof.

According to an embodiment of the present invention, when the redox polymerization system is applied as described above, the carbonate-based metal salt may serve as a pH adjuster capable of adjusting the pH during the polymerization and, at the same time, may also serve as a reducing agent.

In the case of using a strongly basic substance such as sodium hydroxide which is generally used as a pH adjuster, there is no effect of reducing the amount of volatile organic compounds generated as described above, and even if there is some improvement, the productivity is significantly reduced or there is a risk of excessive foaming at the time of foam formulation by plastisol processing. In the case of using an acidic substance such as potassium phosphate as a pH adjuster, there is a serious problem such as being unsuitable for an environmentally friendly product since the amount of volatile organic compounds produced is significantly increased with respect to the degree of improvement in productivity. Therefore, it is desirable to use a carbonate metal salt in order to achieve all the effects of reducing the amount of volatile organic compounds generated, improving the viscosity and foaming properties of the polymer, and improving productivity.

As described above, in the case of properly controlling and adding the transition metal catalyst while adding the carbonate-based metal salt during the polymerization, by solving the above-mentioned existing problems, all effects such as improvement of productivity and reduction of the amount of the volatile organic compound generated can be achieved, plastisols using them have excellent processability due to excellent viscosity characteristics, and the processed vinyl chloride-based polymer can have excellent foaming properties or heat resistance.

Further, the method for preparing a vinyl chloride-based polymer according to one embodiment of the present invention includes adding a transition metal catalyst when the polymerization conversion rate is in the range of 5% to 35%, wherein since the addition of the transition metal catalyst during the polymerization process improves the reduction of the reaction rate due to the use of the carbonate-based metal salt, excellent productivity can be secured.

According to an embodiment of the present invention, the transition metal catalyst is added when the polymerization conversion rate is in the range of 5% to 35%, and, in terms of improving productivity and improving viscosity and foaming property of the polymer, preferably, the transition metal catalyst may be added when the polymerization conversion rate is in the range of 10% to 30%, and more preferably, the transition metal catalyst may be added when the polymerization conversion rate is in the range of 15% to 25%. In the case where the transition metal catalyst is added when the polymerization conversion is less than 5%, the reactivity may be improved, but since the formation of fine particles is promoted at the initiation stage of the reaction, the viscosity characteristics of the finally prepared polymer may be lowered. In the case where the transition metal catalyst is added when the polymerization conversion rate is more than 35%, since the effect of promoting the formation of polymer particles at the reaction initiation stage is reduced, the effect of shortening the reaction time is not significant, and therefore, it is predicted that the productivity will not be improved.

In addition, there is no limitation on the method of adding the transition metal catalyst, and the method of adding the transition metal catalyst may be appropriately selected from a batch addition method, a continuous addition method, and a fractional addition method, and may be used according to the physical properties of the polymer to be produced, wherein the desired effect of the present invention can be sufficiently achieved even in the case of using the continuous addition method or the fractional addition method, but the batch addition method is preferable in terms of improvement in productivity of the polymer to be produced.

According to an embodiment of the present invention, the transition metal catalyst may be added in an amount of 0.01 to 7.5ppm, preferably 0.03 to 6.0ppm, more preferably 0.05 to 5.0ppm, based on the total weight of the vinyl chloride-based monomer. The transition metal catalyst is a substance capable of improving reactivity by promoting the activity of an initiator, wherein the reactivity can be improved even with a smaller amount of the initiator when the amount of the transition metal catalyst is large, but in the case of excessively containing the transition metal catalyst in an amount of more than 7.5ppm, the viscosity increases due to the promotion of the formation of fine particles, and the foaming property deteriorates due to the significant deterioration of foam color due to the residue of the metal catalyst after polymerization. When the amount of the transition metal catalyst added is 0.01ppm or less, the effect of improving productivity may not be obtained because the amount of the transition metal catalyst added is too small.

Further, since a carbonate-based metal salt is used in the redox polymerization system, the present invention has an effect that the reactivity can be improved to an excellent level even if a small amount of a transition metal catalyst is used.

The transition metal catalyst according to one embodiment of the present invention is not limited as long as it is a transition metal compound for preparing a vinyl chloride-based polymer, and the transition metal catalyst may specifically include copper sulfate, iron sulfate, or a mixture thereof. Copper sulfate canTo comprise copper (I) sulfate (Cu)₂SO₄) Copper (II) sulfate (CuSO)₄) Or mixtures thereof, the iron sulfate may comprise iron (II) sulfate (FeSO)₄) Iron (III) sulfate (Fe)₂(SO₄)₃) Or mixtures thereof.

The reaction may be carried out by further adding additives, for example, 0.5 to 2.0 parts by weight of an electrolyte, 0.1 to 2.0 parts by weight of a chain transfer agent and a reaction inhibitor, as necessary, based on 100 parts by weight of the vinyl chloride-based monomer.

When the pressure in the reactor was 3.0kgf/cm²To 5.0kgf/cm²Within the range of (a), the polymerization performed according to an embodiment of the present invention may be terminated.

In addition, according to the present invention, there may be further included a step of recovering and drying the vinyl chloride-based polymer prepared in the form of latex, wherein the drying is not particularly limited in this case and may be performed by a method known in the art, and the drying may be specifically performed according to a spray drying method. Before drying, a step of dehydration and washing may be further included.

2. Vinyl chloride-based polymer and plastisol

The present invention provides a vinyl chloride-based polymer prepared by the above preparation method and a plastisol including a plasticizer.

The vinyl chloride-based polymer according to the present invention is produced by the above production method, wherein since the polymer is a vinyl chloride-based polymer in which the amount of volatile organic compounds generated is considerably small, the properties of the polymer can be equal to or superior to those of conventional vinyl chloride-based polymers.

For example, the vinyl chloride-based polymer according to the present invention may be a paste-like vinyl chloride-based polymer.

The plastisol according to an embodiment of the present invention may further include 40 to 180 parts by weight, 80 to 160 parts by weight, or 100 to 140 parts by weight of a plasticizer based on 100 parts by weight of the vinyl chloride-based polymer, and may further include additives such as a dispersion diluent, a heat stabilizer, a viscosity modifier, and a foaming agent, as needed.

The expression "plasticizer" in the present invention may refer to an organic additive substance that acts to improve the high-temperature moldability of a thermoplastic resin by adding to the resin to improve the thermoplasticity.

Plasticizers are known in the art as being useful as plasticizers and additives.

Since the plastisol according to the embodiment of the present invention has excellent viscosity characteristics by including the vinyl chloride-based polymer prepared by the above-described preparation method, the plastisol may have excellent processability as well as excellent other performance characteristics and foaming properties.

Hereinafter, the present invention will be described in more detail based on specific embodiments. However, the following examples are provided only to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1

185kg of polymerization water, 40g of a first emulsifier (sodium lauryl sulfate), 110g of a water-soluble initiator (potassium persulfate, KPS) and 150g of potassium carbonate (K)₂CO₃) Was charged into a 500L high pressure reactor, and then the reactor was evacuated while stirring. 185kg of vinyl chloride monomer was charged into the reactor under vacuum, and then the temperature of the reactor was raised to 50 ℃ to conduct polymerization. At the start of the polymerization, 18kg of a second emulsifier (sodium lauryl sulfate) was continuously added to the reactor for 5 hours. When the polymerization conversion was 20%, copper sulfate (CuSO) was added in an amount of 0.05ppm based on the weight of vinyl chloride monomer₄) The reaction was continued. When the pressure of the reactor reached 4.0kgf/cm²When the reaction is completed, the unreacted vinyl chloride monomer is recovered and removed to prepare a vinyl chloride polymer latex. Solid vinyl chloride polymer was prepared by spray drying a vinyl chloride polymer latex.

Example 2

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was added in an amount of 5ppm based on the weight of vinyl chloride monomer at a polymerization conversion rate of 20% in example 1.

Example 3

Except that sodium bicarbonate (NaHCO) was added₃) A vinyl chloride polymer was prepared in the same manner as in example 1, except that potassium carbonate in example 1 was replaced.

Example 4

A vinyl chloride polymer was prepared in the same manner as in example 3, except that copper sulfate was added in an amount of 5ppm based on the weight of vinyl chloride monomer at a polymerization conversion rate of 20% in example 3.

Example 5

Except that sodium carbonate (Na) is added₂CO₃) A vinyl chloride polymer was prepared in the same manner as in example 1, except that potassium carbonate in example 1 was replaced.

Example 6

A vinyl chloride polymer was prepared in the same manner as in example 5, except that copper sulfate was added in an amount of 5ppm based on the weight of vinyl chloride monomer at a polymerization conversion rate of 20% in example 5.

Example 7

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was added at the polymerization conversion of 10% in example 1.

Example 8

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was added at the polymerization conversion of 10% in example 3.

Example 9

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was added at the polymerization conversion of 10% in example 5.

Comparative example 1

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate and sodium carbonate were not added in example 1.

Comparative example 2

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was not added in example 1.

Comparative example 3

A vinyl chloride polymer was prepared in the same manner as in example 3, except that copper sulfate was not added in example 3.

Comparative example 4

A vinyl chloride polymer was prepared in the same manner as in example 5, except that copper sulfate was not added in example 5.

Comparative example 5

A vinyl chloride polymer was prepared in the same manner as in example 1, except that, in the polymerization initiation stage (conversion of 0%) in example 1, potassium carbonate was added together with copper sulfate.

Comparative example 6

A vinyl chloride polymer was prepared in the same manner as in example 3, except that, when sodium bicarbonate was added at the polymerization initiation stage (conversion of 0%) in example 3, copper sulfate was added together.

Comparative example 7

A vinyl chloride polymer was prepared in the same manner as in example 5, except that, in the polymerization initiation stage (conversion of 0%) in example 5, sodium carbonate was added together with copper sulfate.

Comparative example 8

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was added in an amount of 10ppm based on the weight of vinyl chloride monomer in example 1.

Comparative example 9

A vinyl chloride polymer was prepared in the same manner as in example 3, except that copper sulfate was added in an amount of 10ppm based on the weight of vinyl chloride monomer in example 3.

Comparative example 10

A vinyl chloride polymer was prepared in the same manner as in example 5, except that copper sulfate was added in an amount of 10ppm based on the weight of vinyl chloride monomer in example 5.

Comparative example 11

A vinyl chloride polymer was prepared in the same manner as in example 2, except that copper sulfate was added at the polymerization conversion of 50% in example 2.

Comparative example 12

A vinyl chloride polymer was prepared in the same manner as in example 4, except that copper sulfate was added at the polymerization conversion of 50% in example 4.

Comparative example 13

A vinyl chloride polymer was prepared in the same manner as in example 6, except that copper sulfate was added at the polymerization conversion of 50% in example 6.

Comparative example 14

A vinyl chloride polymer was prepared in the same manner as in example 1, except that copper sulfate was continuously added from the polymerization initiation stage (conversion: 0%) to the polymerization conversion: 80% in example 1.

Comparative example 15

A vinyl chloride polymer was prepared in the same manner as in example 2, except that copper sulfate was continuously added from the polymerization initiation stage (conversion: 0%) to the polymerization conversion: 80% in example 2.

Comparative example 16

A vinyl chloride polymer was prepared in the same manner as in example 3, except that copper sulfate was continuously added from the polymerization initiation stage (conversion: 0%) to the polymerization conversion: 80% in example 3.

Comparative example 17

A vinyl chloride polymer was prepared in the same manner as in example 4, except that copper sulfate was continuously added from the polymerization initiation stage (conversion: 0%) to the polymerization conversion: 80% in example 4.

Comparative example 18

A vinyl chloride polymer was prepared in the same manner as in example 5, except that copper sulfate was continuously added from the polymerization initiation stage (conversion: 0%) to the polymerization conversion: 80% in example 5.

Comparative example 19

A vinyl chloride polymer was prepared in the same manner as in example 6, except that copper sulfate was continuously added from the polymerization initiation stage (conversion: 0%) to the polymerization conversion: 80% in example 6.

Comparative example 20

A vinyl chloride polymer was prepared in the same manner as in example 1, except that 17g of sodium hydroxide (NaOH) was added instead of the potassium carbonate in example 1.

Comparative example 21

A vinyl chloride polymer was prepared in the same manner as in example 2, except that 17g of sodium hydroxide (NaOH) was added instead of the potassium carbonate in example 2.

Table 1 below shows the conditions for adding the pH adjuster and copper sulfate in examples 1 to 9 and comparative examples 1 to 21.

[ Table 1]

Experimental example 1

1) Measurement of polymerization time

The measurement was made until the reactor pressure reached 4.0kgf/cm²The polymerization time at the time of terminating the reaction is shown in Table 2 below.

2) TSC (%) measurement

1.5g each of the vinyl chloride polymer latexes prepared in examples and comparative examples (before drying) was placed on a MX-50 moisture analyzer (A & D Co., Ltd.), and the Total Solid Content (TSC) was measured at 150 ℃ after 30 minutes, as shown in Table 2 below.

3) Volatile weight loss measurement

The loss on volatility was measured according to DIN 75-201B standard using a atomization tester (Horizon-FTS, Thermo Fischer Scientific Inc.). After setting the atomization tester (Horizon-FTS, Thermo Fischer Scientific Inc.) to 100 ℃, the weight of the empty foil was measured and recorded. Thereafter, 10g each of the vinyl chloride polymer samples prepared in examples and comparative examples was weighed in an empty beaker and placed in a cylinder, and the upper end of the cylinder was covered with an aluminum foil to conduct a sealing treatment. Thereafter, the cylinder was heated at 100 ℃ for 16 hours, the aluminum foil was taken out, the weight thereof was measured after 4 hours, and the value obtained by subtracting the measured weight of the heat-treated sample from the weight of the initial sample was expressed as a volatile weight loss, and the results thereof are shown in Table 2 below. The higher the volatile weight loss, the greater the amount of volatile organic compounds in the polymer produced.

Experimental example 2

1) Viscosity measurement

100g and 66.7g of diisononyl phthalate (DINP) each of the vinyl chloride polymers prepared in examples and comparative examples were mixed with an EUROSTAR IKA-WERKE mixer at a speed of 800 rpm for 10 minutes, and after preparing each plastisol, the viscosity was measured with a 40mm parallel plate jig and a rheometer (AR2000EX peltier plate, TA instruments) having a gap of 500 μm, and the results thereof are shown in Table 2 below.

2) Measurement of foaming Properties

Each of 100g of the vinyl chloride polymers prepared in the inventive examples and comparative examples, 80g of di (2-propylheptyl) phthalate (DPHP), 3g of Ba/Zn stabilizer and 3g of acrylonitrile-based blowing agent was mixed with an EUROSTAR IKA-WERKE mixer at 800 rpm for 10 minutes to prepare each plastisol, and the prepared plastisol was coated on release paper and coated with a 0.5mm bar, and then a pre-gelled sheet was prepared with a Mathis oven at 150 ℃ for 45 seconds and gelled at 200 ℃ for 90 seconds to prepare a foamed sheet. The whiteness index of the prepared foam pieces was measured using a spectrophotometer (CM-700d) according to ASTM E313-73, and the results are shown in Table 2 below. The higher the whiteness index measured, the better the thermal stability, and good thermal stability, meaning good foaming properties, such as foam color quality.

[ Table 2]

As shown in table 2, for examples 1 to 9 according to the present invention, in which vinyl chloride polymers were prepared by adding carbonate-based metal salts and adding transition metal catalysts in an amount of 0.01ppm to 7.5ppm based on the weight of monomers at a conversion rate ranging from 5% to 35%, it was confirmed that the viscosity and the foam color were improved while obtaining vinyl chloride polymers having less volatile weight loss, while productivity was further improved, as compared to comparative examples 1 to 21 failing to satisfy one or more conditions.

Specifically, for comparative examples 2 to 4, in which a vinyl chloride polymer having less volatile weight loss can be prepared without using a transition metal catalyst while adding a carbonate-based metal salt, but since the decomposition activity of the initiator is decreased due to a change in pH value at the initial stage of polymerization, it can be confirmed that the polymerization time is significantly delayed and the viscosity and foam color of the plastisol using the prepared polymer are also decreased, compared to comparative example 1 and examples, in which no pH regulator is used.

In addition, for comparative examples 5 to 7, in which the transition metal catalyst and the carbonate-based metal salt are added in the initial stage of the reaction, the polymerization time is shortened, but since the presence of the transition metal catalyst affects the droplet stability of the monomer in the initial stage of the reaction, the formation of fine particles is promoted. The foam color of the plastisol using the prepared polymer was reduced, and particularly the viscosity property was significantly reduced, for example, the viscosity was excessively increased, and thus, it could be confirmed that it was impossible to industrially use the polymers of comparative examples 5 to 7.

Further, for comparative examples 8 to 10, in which the transition metal catalyst was excessively added in an amount of 10ppm based on the weight of the monomer, it could be confirmed that the amount of volatile organic compounds in the polymer was large due to the high volatile weight loss of the produced polymer, and the viscosity property was deteriorated due to the increase of the viscosity of the plastisol using the polymer about 2 times or more as compared to that in the examples, and particularly the quality was deteriorated during the preparation of molded articles due to the significant deterioration of the foam color. Therefore, it could be confirmed that the polymers of comparative examples 8 to 10 could not be used industrially.

In addition, for comparative examples 11 to 13, in which the injection time of the transition metal catalyst was outside the range of the example according to the present invention, since more than half of the monomer had been stabilized by forming a polymer, there may be no effect of initially promoting particle formation. Therefore, there is almost no effect of improving productivity, which is similar to comparative example 1 to which nothing is added, and it can be confirmed that comparative examples 11 to 13 have plastisol properties similar to comparative examples 2 to 4 to which no transition metal is added, because the physical properties of the polymer are not affected either.

Further, for comparative examples 14 to 19, in which the injection time is outside the specific injection time of the transition metal catalyst, and the continuous addition is performed according to the embodiment of the present invention, since the amount of the transition metal catalyst added per unit time is very small, comparative examples 14 to 19 have almost no effect according to the addition of the transition metal catalyst, and thus the effect of improving productivity and the effect of improving formulation properties may not be achieved. Alternatively, in the case where a sufficient amount of the transition metal catalyst is added to possibly obtain the effect of productivity improvement, since the starting point of continuous addition is earlier than the specific time point in the present invention, it can be confirmed that comparative examples 14 to 19 have the same problems as comparative examples 5 to 7 in which the transition metal catalyst is added from the initial stage of the reaction.

In addition, in comparative examples 20 and 21 in which sodium hydroxide was added without adding the carbonate-based metal salt according to the embodiment of the present invention, it was confirmed that a small amount of sodium hydroxide was added in order to prevent the caking phenomenon that may occur due to the sudden change in pH and to obtain a normal polymer, and in this case, the effect of improving the productivity was not obtained. In particular, since sodium hydroxide did not play a role in reducing the loss of volatility, it was confirmed that the loss of volatility was lower than that in the examples.

In the present invention, in examples 1 to 9, by using a carbonate-based metal salt as a pH adjuster, since a transition metal catalyst is added in the preparation of an eco-friendly vinyl chloride polymer having low volatile weight loss and the injection time and amount of the transition metal catalyst are controlled, it can be confirmed that productivity is improved and, at the same time, formulation properties of plastisol, such as viscosity characteristics and foaming properties, can be improved to an excellent level.