KR102365526B1 - Method for preparing vinyl chloride polymer and vinyl chloride polymer prepared therefrom - Google Patents

Abstract

In the present invention, it comprises the step of polymerizing the vinyl chloride-based monomer and the step of increasing the temperature from the point in time when 60% or more and less than 75% of the total polymerization time after the polymerization is started. A method for producing a vinyl chloride-based polymer having improved productivity by raising the temperature so as to be more than 100 and 110% or less, and a method for producing a vinyl chloride-based polymer having an excellent degree of polymerization are provided.

Description

Method for producing a vinyl chloride-based polymer and a vinyl chloride-based polymer prepared accordingly

The present invention relates to a method for producing a vinyl chloride-based polymer capable of producing a vinyl chloride-based polymer having high productivity and excellent polymerization degree, and to a vinyl chloride-based polymer prepared thereby.

The vinyl chloride-based polymer is a homopolymer of vinyl chloride or a hybrid polymer containing 50% or more of vinyl chloride. In addition, it can provide a molded article having excellent physical and chemical properties, such as mechanical strength, weather resistance, chemical resistance, and the like, and thus is widely used in various fields.

Polymerization methods of the vinyl chloride-based polymer include emulsion polymerization and suspension polymerization. In general, suspension polymerization of vinyl chloride-based monomers is performed in a batch manner. After adding vinyl chloride-based monomers and initiator additives, the polymerization reaction is initiated by increasing the temperature to the polymerization temperature by circulating hot water in the jacket of the polymerization reactor, When heat is generated by the exothermic reaction, the vinyl chloride-based polymer is polymerized by flowing cooling water to the jacket to maintain the polymerization temperature. An example of such a polymerization method is disclosed in Korean Patent Publication No. 2010-0005281 and the like.

When a vinyl chloride-based polymer is prepared by suspension polymerization, it is polymerized into particles of about 150 μm, so there is an advantage that it can be processed immediately after drying. In addition, the polymerized vinyl chloride-based polymer has excellent electrical insulation properties and excellent chemical resistance, and is often used as a chemical container.

Since the advantages of suspension polymerization exist, the demand for vinyl chloride-based polymers by suspension polymerization is gradually increasing. has been steadily progressing.

As a method to increase polymerization productivity, conventionally, the heat removal capacity of a reflux condenser (RCN), a jacket, and a baffle, which are a kind of heat removal system, is increased, and the polymerization time is shortened through an increase in the initiator to increase productivity. Methods to improve have been suggested.

As another method, a method of shortening polymerization and improving productivity by increasing the initiator amount by increasing the heat removal effect by replacing the cooling water with chilled water has been proposed.

However, all of the conventionally proposed methods for improving productivity require a new heat removal system to be installed, and as the heat removal performance is improved, a lot of cost is incurred in terms of maintenance as well, thereby increasing the manufacturing cost compared to the conventional method.

Accordingly, there is a need for a method for improving productivity without installing new equipment or without repair work.

In general, polymerization of vinyl chloride-based polymers does not generate a certain amount of heat during the polymerization time due to polymerization characteristics, and there is a change in the degree of heat generation for each section, such as the maximum amount of heat generated in a specific section. This shows a marked decline. The inventors of the present invention paid attention to the point that increasing the reactivity at the end of polymerization can immediately improve the polymerization productivity from the above phenomenon, and as a method of increasing the reactivity at the end of polymerization, they invented the vinyl chloride-based manufacturing method of the present invention.

Korean Patent Publication No. 2010-0005281

An object of the present invention is to solve the above problems and to provide a method for producing a vinyl chloride-based polymer capable of improving the reactivity at the end of polymerization by controlling the polymerization temperature after the middle of polymerization and, as a result, improving productivity. .

Another object of the present invention is to provide a vinyl chloride-based polymer prepared according to the above production method and having a polymerization degree of 990 to 1100.

In order to solve the above problems, in accordance with an embodiment of the present invention the step of initiating polymerization of a vinyl chloride-based monomer (step 1); and a step (step 2) of increasing the temperature from the point in time when 60% or more and less than 75% of the total polymerization time after initiating the polymerization (step 2); It provides a method for producing a vinyl chloride-based polymer by raising the temperature as much as possible.

According to another embodiment of the present invention, a vinyl chloride-based polymer prepared by the above manufacturing method and having a polymerization degree of 990 to 1100 is provided.

In the method for producing a vinyl chloride-based polymer according to the present invention, by controlling the temperature after the middle of polymerization, reactivity at the end of polymerization can be improved, and as a result, productivity can be improved.

In addition, in the method for producing a vinyl chloride-based polymer according to the present invention, the polymerization degree of the vinyl chloride-based polymer prepared by controlling the temperature increase is maintained at an excellent level despite the temperature increase process, and the prepared vinyl chloride-based polymer includes There is an effect of excellent quality of molded products, etc.

In addition, since the method for producing a vinyl chloride-based polymer according to the present invention proceeds with the temperature increase process while continuously operating the heat removal facility until the end of the reaction, it is easy to control the temperature when the temperature is raised, and it is possible to prevent a sudden temperature increase during the reaction, It has the effect of improving the stability of the process.

Hereinafter, the present invention will be described in more detail to help the understanding of the present invention.

The terms or words used in the present specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

As used herein, the term average particle diameter (D ₅₀ ) may be defined as a particle diameter corresponding to 50% of the cumulative amount of the number of particles in the particle size distribution curve of the particles. The average particle diameter (D ₅₀ ) may be measured using, for example, a laser diffraction method. In general, the laser diffraction method can measure a particle diameter of several mm from a submicron region, and can obtain results of high reproducibility and high resolution.

A method for producing a vinyl chloride-based polymer according to an embodiment of the present invention includes the steps of initiating polymerization of a vinyl chloride-based monomer (step 1); and a step (step 2) of increasing the temperature from the point in time when 60% or more and less than 75% of the total polymerization time after initiating the polymerization (step 2); to heat it up as much as possible.

Hereinafter, each step will be described in detail.

Step 1

Step 1 according to an embodiment of the present invention is a step of initiating polymerization of the vinyl chloride-based monomer.

The polymerization may be any one selected from commonly applied polymerization methods, such as suspension polymerization, emulsion polymerization, seed polymerization, etc. In the present invention, polymerization may be preferably performed using a suspension polymerization method, and suspension polymerization is limited However, it may be done in a batch manner.

In the present invention, "initiating polymerization" means the time point at which the vinyl chloride-based monomer is added, specifically, it means to start the polymerization of the vinyl chloride-based monomer by adding the vinyl chloride-based monomer and adjusting the polymerization temperature to an appropriate temperature. do.

In the method for producing a vinyl chloride-based polymer according to an embodiment of the present invention, the suspension polymerization is carried out in a polymerization reactor filled with additives such as a solvent, a polymerization initiator, one or more protective colloid assistants, and, if necessary, a molecular weight regulator. It can be carried out by adding a system monomer and reacting.

Here, the "filled polymerization reactor" refers to a state in which additives such as a solvent, a polymerization initiator, one or more protective colloid assistants, and optionally a molecular weight regulator are added into the polymerization reactor before the vinyl chloride monomer is added. .

In the present invention, "before starting polymerization" means before adding the vinyl chloride monomer to the filled reactor.

The vinyl chloride-based polymer produced by the method for producing the vinyl chloride-based polymer according to an embodiment of the present invention is not only a polymer made of pure vinyl chloride monomer, but also a vinyl chloride monomer as a main component and copolymerizable with the vinyl chloride monomer. It may be a copolymer with a system monomer. In this case, when the vinyl chloride-based polymer is a copolymer of a vinyl chloride monomer and a vinyl-based monomer, 50% or more of vinyl chloride may be contained in the copolymer.

Accordingly, the vinyl chloride-based monomer usable during the suspension polymerization may be a single vinyl chloride material; Alternatively, it may be a mixture of vinyl chloride, and a vinyl-based monomer copolymerizable with the vinyl chloride. The vinyl monomer is not particularly limited, but olefin compounds such as ethylene, propylene and butene, vinyl esters such as vinyl acetate, vinyl propionate, and vinyl stearate, and unsaturated nitriles such as acrylonitrile Vinyl alkyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl octyl ether, vinyl lauryl ether, vinylidene halides such as vinylidene chloride, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid , unsaturated fatty acids such as 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, butyl benzyl maleate, diallyl phthalate, etc. and monomers, and any one or a mixture of two or more thereof may be used.

In addition, the solvent may be deionized water, and the amount of the solvent may be appropriately adjusted depending on the size of the polymerization reactor and the amount of monomer used, for example, based on 100 parts by weight of the vinyl chloride-based monomer used for the suspension polymerization. 70 parts by weight or more, preferably 70 to 120 parts by weight.

In addition, the polymerization initiator may be used in an amount of 0.02 to 0.2 parts by weight based on 100 parts by weight of the vinyl chloride-based monomer used for polymerization. If the polymerization initiator is used in an amount of less than 0.02 parts by weight, the polymerization reaction time is prolonged, the conversion rate to the vinyl chloride-based polymer is lowered, and there is a risk of lowering productivity, and when used in excess of 0.2 parts by weight, the polymerization process Among them, the polymerization initiator is not completely consumed and remains in the finally prepared vinyl chloride-based polymer slurry, which may reduce thermal stability and the like. More specifically, the polymerization initiator may be used in an amount of 0.04 to 0.12 parts by weight based on 100 parts by weight of the vinyl chloride-based monomer.

Specifically, the polymerization initiator is a peroxide-based compound such as dicumyl peroxide, dipentyl peroxide, di-3,5,5-trimethyl hexanoyl peroxide or dilauryl peroxide; peroxydicarbonate-based compounds such as diisopropylperoxydicarbonate, di-sec-butylperoxydicarbonate or di-2-ethylhexylperoxydicarbonate; peroxyester compounds such as t-butylperoxy pivalate, 1,1,3,3-tetramethylbutylperoxy neodecanoate or t-butylperoxy neodecanoate; azo compounds such as azobis-2,4-dimethylvaleronitrile; hydroperoxide-based compounds such as t-butyl hydroperoxide; or a sulfate-based compound such as potassium persulfate or ammonium persulfate, and any one or a mixture of two or more thereof may be used.

In addition, the protective colloidal aid maintains the stability of the vinyl chloride-based monomer in the production process of the vinyl chloride-based polymer, and the average particle diameter, apparent specific gravity (BD), particle size distribution, and plasticizer of the vinyl chloride-based polymer to a target level. It can be used for the purpose of obtaining physical properties such as water absorption (CPA), and as the protective colloidal aid, for example, a vinyl alcohol-based agent having a degree of hydration of 30 to 90% and a viscosity of 4% aqueous solution at room temperature of 5 to 100 cps Resin, at least one selected from the group consisting of cellulose and unsaturated organic acids having a methoxy group content of 15 to 40% by weight, a propyl hydroxide group of 3 to 20%, and a viscosity of 10 to 20,000 cps of a 2% aqueous solution measured at 23±5 and preferably a vinyl alcohol-based resin having a hydration degree of 30 to 90%, and a viscosity of a 4% aqueous solution at room temperature of 5 to 100 cps, a methoxy group of 15 to 40%, and a propyl hydroxide group of 3 to 20% and cellulose having a viscosity of 10 to 20,000 cps of a 2% aqueous solution measured at room temperature, or a mixture thereof. In this case, the unit % of the degree of hydration may be interpreted as weight %.

The protective colloidal auxiliary agent may be 0.03 to 0.5 parts by weight, preferably 0.05 to 0.15 parts by weight, based on 100 parts by weight of the vinyl chloride-based monomer. If the amount of the polymerization dispersant used is 0.03 parts by weight or more, droplet stability may be improved, and if it is 0.5 parts by weight or less, coarse PVC particles may be formed, and the effect of improving droplet stability is insufficient.

On the other hand, in one example of the present invention, the protective colloid aid may include a mixture of two or more vinyl alcohol-based resins having different degrees of hydration, for example, a vinyl alcohol-based resin having a hydration degree of more than 50% and 90% or less (high water content). and a mixture of a vinyl alcohol-based resin (low hydration resin) having a hydration degree of 30% to 50%, and in another embodiment, for example, a vinyl alcohol-based resin having a hydration degree of 85 to 98%. Contains a mixture of a resin (high hydration resin), a vinyl alcohol-based resin having a hydration degree of 62 to 82% (medium hydration resin), and a vinyl alcohol-based resin having a hydration degree of 50 to 60% (a low hydration resin) The content of each vinyl alcohol-based resin constituting the mixture is 0.01 to 0.06 parts by weight of the vinyl alcohol-based resin having the degree of hydration of 85 to 98% based on 100 parts by weight of the vinyl chloride monomer, and the degree of hydration is 62 To 82% may be 0.01 to 0.06 parts by weight of the vinyl alcohol-based resin, and 0.01 to 0.03 parts by weight of the vinyl alcohol-based resin having a hydration degree of 50 to 60%.

In addition, the protective colloid aid may include the cellulose in addition to the vinyl-based alcohol-based resin, wherein the cellulose may be included in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the vinyl chloride monomer, The cellulose may include methyl cellulose, hydroxyethyl cellulose, or hydroxypropyl methyl cellulose, and any one or a mixture of two or more thereof may be used. Among them, it may be hydroxypropylmethylcellulose, and the cellulose is more specifically 15 to 40% by weight of a methoxy group, 3 to 20% of a propyl hydroxide group, and a viscosity of a 2% aqueous solution measured at 23±5 of 10 to 20,000 It may be cps.

In addition, the unsaturated organic acid polymer may include an acrylic acid polymer, a methacrylic acid polymer, an itaconic acid polymer, a fumaric acid polymer, a maleic acid polymer, or a succinic acid polymer, and any one or a mixture of two or more thereof may be used.

In addition, in the suspension polymerization, additives such as a polymerization regulator, a chain transfer agent, a pH regulator, an antioxidant, a crosslinking agent, an antistatic agent, a scale inhibitor, and a surfactant may be additionally added, if necessary, in addition to the active ingredients described above. The type and content of is not particularly limited and can be used in a conventional type and content known in the art. The additive may be added at any time at the beginning of suspension polymerization, during or after polymerization, and may be added in batches or continuously.

In addition, the suspension polymerization may be carried out in a reaction temperature range of 30 to 80 , more specifically 40 to 70 , and even more specifically 50 to 60 . In addition, since polymerization of vinyl chloride-based polymers is an exothermic reaction, a heat removal process through a reactor jacket and R/CN (Reflux Condensor) may be performed together to control the desired temperature during suspension polymerization. Accordingly, the method for producing a vinyl chloride-based polymer according to an embodiment of the present invention may include a heat removal process for maintaining the polymerization temperature during suspension polymerization. In other words, according to an embodiment of the present invention, the step of removing heat from the start of the polymerization of step 1 to the time of terminating the polymerization may be included.

Step 2

Step 2 according to an embodiment of the present invention is a step of increasing the late-stage reactivity, which may have lower reactivity by increasing the polymerization temperature after the middle of polymerization.

Specifically, it includes raising the temperature from the point in time when 60% or more and less than 75% of the total polymerization time after the polymerization in step 1 is started, and the polymerization temperature after the temperature increase is 101 to 110% of the polymerization temperature before the temperature increase. .

The polymerization reaction of the vinyl chloride-based monomer according to an embodiment of the present invention is an exothermic reaction, and the reaction may be a reaction in which the reaction rate and reactivity increase as the temperature rises. Therefore, when the temperature raising step of step 2 of the present invention is performed, the reactivity that is normally lowered at the end of polymerization is increased, and thus productivity can be ultimately improved.

In addition, in the present invention, even in step 2, since the heat removal process in step 1 is continuously performed until the end of the reaction, even if the temperature increase process is performed, the temperature at which the temperature is raised can be easily controlled. Therefore, it is possible to prevent the temperature from rising rapidly, and thus, there is an effect of increasing the stability of the manufacturing process.

According to an embodiment of the present invention, the temperature increase time may be 60% or more and less than 75%, preferably 60 to 70% of the total polymerization time. If the temperature rise time is less than 60% of the polymerization time, the temperature rises before the polymer enters the stabilization period, so the degree of polymerization cannot be controlled, so that the polymerization degree of the vinyl chloride-based polymer produced may decrease. A problem in that the quality of a molded article containing a vinyl chloride-based polymer is deteriorated may occur. On the other hand, when the temperature increase time is 75% or more, the temperature increase time is too late, and the polymerization is terminated in a state where the productivity is not improved to the desired level. Since the end point is approaching, improved productivity cannot be obtained even if the temperature is increased. Therefore, the temperature increase point of the present invention must be satisfied in order to improve productivity and maintain the quality of the polymer to be produced at an excellent level.

In addition, according to an embodiment of the present invention, the temperature after the temperature increase is more than 100% and 110% or less of the polymerization temperature before the temperature increase, preferably 101 to 109%, more preferably 105 to 110% of the temperature can be there is. If the temperature after the temperature rise is 100% or less of the polymerization temperature, the effect of increasing the productivity at the end of polymerization cannot be obtained because the temperature is not increased. Since a vinyl-based polymer can be produced, a problem of poor polymerization degree of the vinyl chloride-based polymer may occur. Specifically, in the case of vinyl chloride-based polymers, processing conditions may be different depending on the degree of polymerization, so when processing vinyl chloride-based polymers having different degrees of polymerization as described above, processability deteriorates and the quality of molded products may deteriorate. . As such, since a change in the degree of polymerization may occur according to a change in temperature during polymerization, productivity is improved only when the temperature rise temperature range of the present invention is satisfied, and at the same time, a vinyl chloride-based polymer having an excellent degree of polymerization quality can be prepared. .

In addition, according to an embodiment of the present invention, the step 2 may proceed until the polymerization is terminated, and if the temperature is raised stepwise until the polymerization is terminated, the temperature increase rate is not particularly limited, but for example, the temperature increase rate may be 0.0005 to 0.15 °C/min, preferably 0.01 to 0.1 °C/min. In addition, preferably, the temperature may be increased while maintaining the temperature increase rate constant.

In the case where the temperature is rapidly increased at once without raising the temperature stepwise after the temperature increase in Step 2, it is difficult to control the heat removal system that manages the temperature during the reaction, and the reactivity rapidly increases according to the temperature increase process, so the temperature and pressure in the reactor If the temperature rises rapidly, the heat removal system may not be able to easily control it, resulting in a risk.

According to an embodiment of the present invention, the antioxidant is added at the end of the suspension polymerization, specifically, when the pressure change is 0.5 kg/cm ² to 1.5 kg/cm ² based on the equilibrium pressure at the polymerization temperature in the polymerization reactor. can be put in Antioxidants are those that act to stop polymerization by reacting with radicals of the vinyl chloride polymer. In general, in the production of a vinyl chloride-based polymer by suspension polymerization, the pressure is kept constant by maintaining the equilibrium state of the liquid and gas phase before a specific conversion rate (critical conversion), whereas after a specific conversion rate, the vapor phase of the vinyl chloride monomer is As it is consumed, the equilibrium pressure is broken, resulting in a drop in pressure. On the other hand, in the present invention, the melt processability of the vinyl chloride polymer can be greatly improved by adding an antioxidant when the pressure is lowered to a certain level to terminate the reaction. As a result, it is possible to increase productivity when manufacturing a processed molded article using the same.

The antioxidant is not particularly limited as long as it is generally used in the preparation of a vinyl chloride-based polymer, and a specific example is triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl). ) propionate], hydroquinone, p-methoxyphenol, t-butylhydroxyanisole, n-octadecyl-3-(4-hydroxy 3,5-di-t-butylphenyl) propionate; 2,5-di-t-butyl hydroquinone, 4,4-butylidenebis (3-methyl-6-t-butyl phenol), t-butyl catechol, 4,4-thio bis (6-t- phenol compounds such as butyl-m-cresol), tocopherol, and non dihydro guaretic acid; amine compounds such as N,N-diphenyl-p-phenylenediamine and 4,4-bis(dimethyl benzyl)diphenylamine; and sulfur compounds such as dodecyl mercaptan and 1,3-diphenyl-2-thiol, and any one or a mixture of two or more thereof may be used.

The antioxidant may be used in an amount of 0.01 parts by weight to 1 part by weight based on 100 parts by weight of the vinyl chloride-based monomer used in the preparation of the vinyl chloride-based polymer. If the content of the antioxidant is less than 0.01 parts by weight, the particle size of the vinyl chloride polymer is excessively increased and there is a fear that fish eyes may occur. Considering the remarkable effect of improving the polymerization efficiency and physical properties of the vinyl chloride polymer according to the use of the protective colloidal auxiliary, the antioxidant may be used in an amount of 0.05 to 1 part by weight based on 100 parts by weight of the vinyl chloride monomer.

The vinyl chloride-based polymer prepared according to the polymerization stop may be in the form of a slurry, and the slurry may be prepared in the form of a final vinyl chloride-based polymer by removing moisture using a fluidized bed dryer under normal reaction conditions.

As the reactor used in the present invention, the shape of a stirrer and a stirring device such as a baffle is not particularly limited, and a stirring device generally used for suspension polymerization of vinyl chloride-based polymers may be used. As a specific example, as a stirrer, agitating blades are single or two pieces of paddles, pitched paddles, bloomers gin, pawdoramaris, turbines, propellers, etc. A stirrer combined with more than one type of stirring blade may be used, and the baffle may be of a plate type, a cylinder type, a D type, a loop type, or a finger type.

The present invention provides a vinyl chloride-based polymer prepared according to the above manufacturing method and having a polymerization degree of 990 to 1100. In the present invention, the degree of polymerization is an average degree of polymerization measured according to JIS K6721-77.

Hereinafter, the present invention will be described in more detail by way of Examples and Experimental Examples. However, the following Examples and Experimental Examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example

Example 1

140 parts by weight of deionized water, 0.05 parts by weight of polyvinyl alcohol having a degree of hydration of 88%, 0.02 parts by weight of polyvinyl alcohol having a degree of hydration of 72%, and a degree of hydration in a stainless polymerization reactor with an internal volume of 1 m ³ equipped with a reflux condenser and stirrer After adding 0.015 parts by weight of 55% polyvinyl alcohol, 0.005 parts by weight of hydroxypropylmethylcellulose, and 0.08 parts by weight of t-butylperoxyneodecanoate (BND), the inside was degassed with a vacuum pump under stirring, and vinyl chloride 100 parts by weight of the monomer was added. The polymerization reaction was carried out while maintaining the temperature in the polymerization reactor at 57 °C. After 135 minutes had elapsed from the start of polymerization, the temperature was started to rise, and the temperature was raised to 58°C until the polymerization was completed. At a time when the polymerization reactor pressure is 1.5 kgf/cm ² , 0.05 parts by weight of triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate as an antioxidant added and the polymerization was stopped. After completion of the reaction, unreacted monomers and resin slurry were respectively recovered from the polymerization reactor, and the recovered resin slurry was dried in a fluidized bed dryer to obtain a vinyl chloride polymer. The measured polymerization time is a total of 213 minutes, and all of the following Examples and Comparative Examples proceed with the same polymerization time.

Example 2

A vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that in Example 1, the temperature was started to rise after 141 minutes had elapsed from the start of polymerization.

Example 3

A vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that in Example 1, the temperature was started to rise after 148 minutes had elapsed from the start of polymerization.

Example 4

In Example 1, a vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that the temperature was raised after 141 minutes had elapsed from the start of polymerization and the temperature was raised to 60° C. until the polymerization was completed.

Example 5

In Example 1, a vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that the temperature was started to rise after 148 minutes had elapsed from the start of polymerization, and the temperature was raised to 62° C. until the polymerization was completed.

Comparative Example 1

In Example 1, a vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that the step of raising the temperature was omitted.

Comparative Example 2

In Example 1, a vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that the temperature was increased after 125 minutes had elapsed from the start of polymerization and the temperature was raised to 58° C. until the polymerization was completed.

Comparative Example 3

In Example 1, in the same manner as in Example 1, except that the temperature was raised to 62° C. until the polymerization was completed and the temperature was raised after 160 minutes had elapsed (the point at which the pressure drop occurred). A vinyl chloride-based polymer was obtained.

Comparative Example 4

In Example 1, a vinyl chloride-based polymer was obtained in the same manner as in Example 1, except that the temperature was started to rise after 148 minutes had elapsed from the start of polymerization, and the temperature was raised to 64° C. until the polymerization was completed.

Experimental example

The average particle diameter, apparent specific gravity, average degree of polymerization, and conversion of the vinyl chloride-based polymers prepared in Examples and Comparative Examples were measured, respectively, and the results are shown in Table 1 below.

1) Average particle diameter (D ₅₀ , ㎛)

The average particle diameter of each vinyl chloride-based polymer was measured according to ISO 13320.

2) Apparent specific gravity (g/cm ³ )

The apparent specific gravity of each vinyl chloride-based polymer was measured according to ASTM D1895.

3) Average degree of polymerization

The average degree of polymerization of each vinyl chloride-based polymer was measured according to ASTM D1243.

4) Conversion rate (%)

By measuring the weight of the initially added vinyl chloride monomer (VCM) and unreacted VCM after the reaction, that is, the weight of recovered VCM (recovery VCM), the conversion rate was calculated as follows.

(initial VCM amount - unreacted VCM amount) / (initial VCM amount) * 100 = conversion (%)

division temperature rise point
(minute) Temperature after temperature rise (℃) Conversion rate (%) average particle diameter
(μm) Apparent specific gravity (g/cm ³ ) average degree of polymerization Example 1 135 58 86.8 168 0.559 1000 Example 2 141 58 86.1 167 0.558 1000 Example 3 148 58 85.6 170 0.561 1000 Example 4 141 60 87.4 171 0.561 1000 Example 5 148 62 88.2 172 0.562 995 Comparative Example 1 - - 85.2 170 0.563 1000 Comparative Example 2 125 58 87.1 171 0.561 985 Comparative Example 3 160 62 86.3 172 0.560 995 Comparative Example 4 148 64 88.7 175 0.567 960

As shown in Table 1, according to an embodiment of the present invention, the temperature increase is started at a time point of 60% or more and less than 75% of the polymerization time after polymerization initiation, and the polymerization temperature after the temperature increase is 101 to 110 of the polymerization temperature before the temperature increase. %, it can be confirmed that the conversion rate is excellent and the polymerization degree is excellent at the same polymerization time as compared to the comparative example out of the scope of the present invention.

Specifically, in Examples 1 to 5 of the present invention, it was confirmed that the conversion rate was high compared to Comparative Example 1 in which the temperature raising step was omitted and the isothermal polymerization was performed, and from this, it can be seen that the productivity was improved.

In addition, all other conditions are the same, but when comparing Comparative Example 2 and Examples 1 to 3, in which the temperature rise time is too early, in Comparative Example 2, it can be confirmed that the polymerization degree of the prepared polymer is significantly lowered because the temperature increase time is too fast. And through this, it can be confirmed that the molded article manufactured by using Comparative Example 2 may not meet the required degree of polymerization and may cause a problem of poor quality. On the other hand, in Examples 1 to 3, unlike Comparative Example 2, since the polymerization degree is maintained at a required level, it can be seen that the quality of the polymer and molded articles produced therefrom will be excellent. In addition, when all other conditions were the same, but compared to Example 5 and Comparative Example 3 with different temperature rise times, Comparative Example 3 had a late heating time, and in particular, the temperature increase was started at the time of pressure drop, and the conversion rate at the same polymerization time It can be confirmed that it is significantly inferior to that of Example 5. Through this, it can be seen that the polymerization method of Comparative Example 3 has lower productivity, whereas in Example 5, the productivity is improved by increasing the reactivity at the end of polymerization.

In addition, all other conditions are the same, but when the temperature is increased to 64 ° C. and Comparative Example 4 and Examples 1 to 5, which are heated to a temperature exceeding 110% of the reaction temperature, Comparative Example 4 has too high a temperature It can be seen that the degree of polymerization is remarkably lowered, and through this, it can be confirmed that the molded article manufactured using Comparative Example 4 also does not meet the required degree of polymerization, resulting in a problem of poor quality. However, in Examples 1 to 5, in which the polymerization temperature was adjusted to a specific range according to an embodiment of the present invention after temperature increase, the polymerization degree was maintained at a required level, and the polymer and the molded article produced therefrom were excellent in quality. know it will do.

As such, in the method for producing a vinyl chloride-based polymer, when it is prepared according to an embodiment of the present invention, it can be confirmed that the productivity is improved, and at the same time as the productivity is improved, the polymerization degree of the produced polymer is excellent, so that the It can be seen that the processability of the vinyl chloride-based polymer and the quality of the manufactured molded article are improved.

Claims (9)

Initiating polymerization of a vinyl chloride-based monomer (step 1); and
Including a; in which the temperature is raised from a point in time when 60% or more and less than 75% of the total polymerization time after the polymerization is started (step 2);
The method for producing a vinyl chloride-based polymer by raising the temperature so that the polymerization temperature after the temperature increase in step 2 is 105% to 110% of the polymerization temperature before the temperature increase.
According to claim 1,
Step 2 is a method for producing a vinyl chloride-based polymer in which the temperature is raised from a time point of 60 to 70% of the total polymerization time after the polymerization is started.
delete According to claim 1,
The method for producing a vinyl chloride-based polymer in which the temperature increase rate in step 2 is 0.01 to 0.1 °C/min.
5. The method of claim 4,
A method for producing a vinyl chloride-based polymer to keep the temperature increase rate constant.
According to claim 1,
The step of raising the temperature of step 2 is a method for producing a vinyl chloride-based polymer that proceeds until the polymerization is terminated.
According to claim 1,
The polymerization is a method for producing a vinyl chloride-based polymer is carried out by a suspension polymerization method.
According to claim 1,
A method for producing a vinyl chloride-based polymer comprising the step of removing heat from the time of starting the polymerization of step 1 to the time of terminating the polymerization.
delete