JPH08193102A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE: To enable a high-quality vinyl chloride polymer to be produced at high efficiency by using a vessel comprising a main body having a thermostat element disposed over a bottom end plate of the main body and tilting toward the bottom center. CONSTITUTION: Vinyl chloride or a mixture thereof with a minor proportion of one or more copolymerizable monomers is polymerized using a thermostatic vessel comprising a main body 1, a thermostat element 5 disposed inside the straight part of the main body, and a thermostat element 5a connected to the element 5 and disposed over a bottom end plate 3 so as to tilt toward the center of the bottom. Thus, high cooling efficiency, high production efficiency, and high polymer product quality, which are effects of the use of a thermostat polymerizer, can be ensured over long. Further, since there is no space between the bottom end plate and the lower end of the thermostat element and/or the partition for fixing the thermostat element, there is no fear of scale deposition or erosion in the bottom part. Hence, higher product quality is attained and equipment maintenance is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride polymer, and in particular to a high quality vinyl chloride polymer,
The present invention relates to a method for producing a vinyl chloride polymer that can be produced with high productivity.

[0002]

2. Description of the Related Art Generally, a tank container used for a polymerization reaction of vinyl chloride or a mixture of vinyl chloride-based copolymerizable monomers (hereinafter collectively referred to as "vinyl chloride-based monomer") is a container. The main body 1'is formed of a pressure-tight sealed container in which dish-shaped end plates are welded to both ends of a cylindrical body, and a jacket 16 for removing heat generation and heating contents is attached to the outside of the container main body 1 '. A jacket-type tank container (Fig. 6) is used.

In this type of tank container, since the container body maintains pressure resistance, the plate thickness of the container is generally large, the coefficient of heat transfer through the wall of the container body is low, and the vinyl chloride monomer which is an exothermic reaction. In the polymerization of, it was difficult to obtain high productivity. Further, in the case of enlarging the tank container, it is necessary to increase the plate thickness of the wall of the container body due to the necessity of strength, and there is a disadvantage that the heat transfer coefficient is further lowered.

Therefore, in order to solve the disadvantage of heat conduction, partition plates 17 are arranged side by side at a right angle to the inner surface of the cylindrical body of the container body 1 ', as shown in FIG. 17
By straddling the inner strip 18 between the tips of the
An internal jacket method in which a spiral heating medium flow passage 19 partitioned by a partition plate 17 is formed between the inner strip 18 and the inner surface of the container body 1 '(JP-A-57-147502).
No.) tank container is proposed. In the tank container of this system, the pressure resistance strength is increased by making the interval between the partition plates 17 smaller than the inner diameter of the container body 1 ', and the inner strip 1
It is possible to reduce the thickness of No. 8 and increase the heat transfer coefficient.

However, while the inner jacket type vessel container has excellent thermal conductivity, a large number of inner strips 18 are welded to each other on the inner surface of the vessel vessel where the contents come into contact during the polymerization reaction of the vinyl chloride monomer. There is a disadvantage due to being exposed to. That is, the welded portion has a rough surface roughness due to its construction, and a welding defect portion exists, but in the polymerization reaction of the vinyl chloride-based monomer, the surface of the contacting portion of the reaction mixture (hereinafter referred to as "wetted portion") If the roughness is rough, polymer scale tends to adhere, and if the adhered / generated scale peels off and is mixed in the product, the quality deteriorates (especially when processed into a film, unmelted matter is left in the film. Remain,
Causes so-called fish eye (FE). When trying to prevent the adhesion of polymer scale that causes such deterioration of quality, extremely smooth the welding lines that exist in large numbers,
It is necessary to introduce special anti-adhesion / removal technology.
There is an inconvenience that the cost of manufacturing and maintaining the equipment increases.

In addition, in the polymerization reaction of vinyl chloride-based monomers, in order to prevent corrosion due to hydrogen chloride generated as the reaction progresses, stainless steel is often used as the material for the inner surface of the vessel. The residual stress due to welding is concentrated in the area. For this reason, when a vinyl chloride-based monomer polymerization reaction is carried out using a tank container of the internal jacket method in which many welding lines are adjacent to the inner surface of the container, there is concern about stress corrosion cracking due to this hydrogen chloride (chlorine ion). Therefore, it is necessary to carefully and continuously inspect the degree of deterioration of the welding line, and maintenance is complicated and inspection costs increase.

[0007] In order to solve the disadvantage of this inner jacket type tank container, the present inventors have proposed a method for producing a vinyl chloride polymer in an aqueous medium, which does not have the above problems.
Partition plates are arranged side by side at a right angle to the outer surface of the inner plate, and by straddling an outer strip between the tips of the partition plates,
A flow path wall having a flow path of a heat medium partitioned by a partition plate between the inner plate and the outer strip (hereinafter referred to as "temperature control element").
) Is formed, and the temperature control element is fixed inside the container body with the outer strip side facing the inner surface of the container body at a distance (hereinafter referred to as "temperature control element type tank container"). In this paper, we proposed a method to carry out the polymerization reaction of vinyl chloride monomer.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to improve the quality of the lower part of the temperature control element by improving the shape of the lower part of the temperature control element when producing a vinyl chloride polymer in a temperature control element type vessel. Another object of the present invention is to provide a method for producing the vinyl chloride polymer.

[0009]

That is, the gist of the present invention is as follows.
Polymerization of vinyl chloride-based monomer in an aqueous medium is carried out by arranging partition plates side by side at a right angle to the outer surface of the inner plate, and straddling an outer strip between the tips of the partition plates. A flow path wall (temperature control element) having a flow path of a heat medium partitioned by a partition plate is formed between the plate and the outer strip,
When performing this temperature control element in a vessel body in which the outer strip side is opposed to the inner surface of the vessel body inside the vessel body and fixed at intervals, connect it to the temperature control element of the cylindrical body of the vessel body. A method for producing a vinyl chloride polymer, characterized in that a tank container in which a temperature control element having a shape inclined toward the center of the bottom of the tank container is provided on the bottom end plate portion of the tank container body is used. Hereinafter, the present invention will be described in detail.

<Tank Container> Tank container main body The temperature control element type tank container (hereinafter sometimes referred to as “polymerization tank”) used in the method of the present invention has the following structure.

That is, as shown in FIGS. 1 to 4, the partition plates 7 are arranged side by side at right angles to the outer surface of the inner plate 6 to form the partition plates 7.
By arranging the outer strip 8 between the tips of the above, the temperature control element 5 having the flow path 9 for the heat medium partitioned by the partition plate 7 is formed between the inner plate 6 and the outer strip 8. The outer diameter of the temperature control element 5 is made smaller than the inner diameter of the tank container, and the outer strip 8 side of the temperature control element 5 is opposed to the inner surface of the container body 1 and fixed at intervals to form a temperature control element type tank container. . At this time, a cylindrical temperature control element is used for the cylindrical body part of the container (hereinafter also referred to as “straight body part”), and the temperature control element of the straight body part is used for the bottom end plate part of the container. A temperature control element having a shape inclined toward the center side of the bottom of the vessel container is connected (hereinafter, the temperature control element provided on the bottom end plate portion of such a vessel is referred to as "bottom temperature control element"). To do.

The shape of the bottom temperature control element is, for example, a conical shape or a truncated cone shape 5 toward the center of the bottom of the tank container.
a (Fig. 1), dish shape 5b (Fig. 3) or hemispherical 5c
(FIG. 4) and the like, and more preferably, it has a shape similar to the bottom end plate of the tank container body. In addition, for the polymerization of vinyl chloride-based monomers, a tank container in which a dish-shaped end plate is welded to the upper and lower parts of a cylindrical straight body is usually used, and conventional knowledge on stirring strength was utilized. The dish-shaped bottom shape as shown in FIG. 3 is particularly preferable because it can be easily designed.

Further, at the connecting portion between the bottom temperature control element and the straight body temperature control element, the inner plate surfaces of both temperature control elements are joined together without a gap by a method such as continuous welding or using a connecting plate. It is preferable that the By adopting such a shape, the lower end of the temperature control element generated in the tank container in which only the cylindrical temperature control element 5 is installed in the straight body portion as shown in FIG. 5 and / or the partition wall 13 for fixing the same. Since the space sandwiched between the bottom end plate 3 and the bottom end plate 3 is eliminated, the amount of the reaction mixture retained during the reaction is reduced, the cleaning can be easily performed, and the possibility of scale adhesion is reduced.

The temperature control element is preferably fixed so that the center line of the temperature control element and the center line of the container substantially coincide with each other. At this time, the inner surface of the container body and the outer surface of the temperature control element (that is, the outer strip side). A gap corresponding to the size difference between the two is formed. To prevent the reaction mixture from penetrating into this gap during the polymerization reaction to form scale,
It is more preferable to seal the upper and lower openings.

In order to seal this opening, the lower end of the bottom temperature control element may be directly sealed to the bottom end plate 3 around the tank container nozzle 12 by continuous welding or the like as shown in FIG. Alternatively, as shown in FIGS. 3 and 4, sealing may be performed via a partition wall. Regarding the upper end of the temperature control element, the partition wall 1 is usually attached to the straight body part 2 or the top end plate 4 of the container.
Attach 3 and seal.

In this way, a gap chamber is formed between the outer surface of the temperature control element 5 fixed inside the container body 1 and the inner surface of the container body 1, and the reaction mixture enters the gap. It is possible to prevent the generation of scale adhesion accompanying this. A partition for sealing the upper part and / or the lower part of this gap is preferably provided with an expansion and contraction absorbing part capable of absorbing expansion and contraction due to heat of the temperature control element,
Further, it is necessary to have a strength that can withstand the temperature and pressure normally used in the polymerization of vinyl chloride-based monomers.

Further, in order to prevent the temperature control element and the welding for sealing the upper and lower portions of the gap between the temperature control element and the container body and the partition wall from being destroyed by the reaction pressure, etc., the inner surface of the container body (mainly the top end plate). (Part) and the inner plate of the temperature control element (hereinafter referred to as "main body chamber") and the internal pressure of the gap chamber are preferably substantially the same from the viewpoint of safety. Does not require the pressure resistance of the partition wall as described above. In this case, the difference between the internal pressure of the inner pressure and the gap chamber body chamber 3 Kg / cm ² or less, preferably 1Kg / cm ² or less, and more preferably to such a 0.7 Kg / cm ² or less.

As a method for making the main chamber and the gap chamber substantially at the same pressure, for example, a method of connecting both chambers by using a communication pipe as shown in FIG. A method of providing an opening or a method of detecting the internal pressure of the main body chamber and the gap chamber and adjusting the pressure in the gap chamber by a separately installed pressurization / decompression device so that the pressure is substantially the same as the internal pressure of the main body chamber, etc. However, it is not particularly limited, and these may be used in combination.

Further, a balance piston type pressure equalizer such as an air cylinder type or a cylinder type for pressurizing the sealing liquid,
The main chamber and the gap chamber may be connected via a diaphragm type pressure equalizer such as a bellows or a diaphragm to reduce the difference in internal pressure between the two chambers. When using a pressure equalizing equipment such as such a communication pipe,
It is preferable to inject a liquid such as water into the main chamber through the opening on the side of the tank container to prevent the scale from adhering to or clogging the opening and its surroundings.

The flow path of the heat medium in the temperature control element 5 may be a single spiral as shown in FIG. 1, the bottom end plate may be spiral, and the body of the container may be serpentine in the circumferential direction. May be formed by a plurality of flow paths, or the flow paths may be divided into a plurality of flow paths. As the heat medium supplied to the flow path, steam, hot water or the like is used for heating, normal temperature water such as industrial water is used for cooling, water separately cooled by a cold water tower or a refrigerator, ethylene glycol or the like. A low-temperature boiling point refrigerant such as a refrigerant or chlorofluorocarbon can be used, but is not particularly limited.

The plate thickness of the inner plate 6 depends on the required strength and the space between the partition plates 7, but since the space between the partition plates 7 is smaller than the body length of the container body 1, The thickness can be reduced to obtain a high heat transfer coefficient. As the material of the inner plate 6, a stainless steel material (pure stainless steel material, stainless steel / carbon steel clad material, etc., especially SUS316L is preferable) or a glass lining material is used in consideration of the corrosion resistance of the liquid contact part as described above. The material is not particularly limited as long as it is a material resistant to stress corrosion cracking due to chlorine ions.

From the viewpoint of preventing scale adhesion, it is preferable that the surface of the inner plate 6 is smooth. In order to make the surface smooth, methods such as buffing and electropolishing that are commonly used in industry can be used without particular limitation. The surface roughness of Rmax is usually 10 μm or less, preferably 3 μm or less, and more preferably 1 μm or less. The Rmax may be measured by using the method specified in JIS B0601.

The welded portion occupies the content surface of the main body chamber side of the tank container manufactured as described above in a remarkably smaller proportion than that of the tank container of the inner jacket type, so that adhesion and formation of polymer scale are less and the obtained product is obtained. Since the quality is good and there is little concern about stress corrosion cracking, the degree of maintenance / inspection (so-called maintenance) may be the same as that of a normal outer jacket type vessel container.

Equipment attached to tank container In the method of the present invention, a reflux condenser may be installed as an additional cooling device. The type and material of the reflux condenser are not particularly limited, and the reflux cooling generally used for polymerization of vinyl chloride-based monomers, such as a multi-tube heat exchanger with stainless steel as the material of the liquid contact part, is used. You can use a vessel. The heat transfer area may be determined according to the required quality of the product type, the degree of heat removal load, and the load control method. The load control method may be a generally used method, such as a method of controlling the amount of cooling medium supplied to the reflux condenser or its temperature.

Further, this reflux condenser is installed in the gas phase part of the tank container, but is installed vertically on the top end plate of the tank container body through a connecting pipe so that retention and sticking of scattered polymer is prevented. It is suitable for prevention. The shape of the stirring blades, baffles, etc., which are the auxiliary equipment of the other tank container (polymerization tank), is not particularly limited, and it is a conventional suspension polymerization method, emulsion polymerization method or fine suspension polymerization method, You can use the equipment and equipment used in.

<Polymerization Prescription> The vinyl chloride polymer as referred to in the present invention means a polymer having vinyl chloride as a main constituent unit, which is obtained by polymerizing a vinyl chloride monomer in an aqueous medium. Say. As a polymerization method of the vinyl chloride-based monomer in an aqueous medium, there are generally a suspension polymerization method, an emulsion polymerization method and a fine suspension polymerization method. Suspension polymerization of vinyl chloride monomer
Usually, it is carried out by polymerizing a vinyl chloride-based monomer in an aqueous medium containing a dispersant in the presence of an oil-soluble polymerization initiator.

Emulsion polymerization of a vinyl chloride monomer is carried out in an aqueous medium in the presence of an emulsifier and a water-soluble polymerization initiator, and fine suspension polymerization is carried out by a vinyl chloride monomer. It is carried out by polymerizing the monomer in an aqueous medium in the presence of an emulsifier and an oil-soluble polymerization initiator, followed by homogenization treatment.

Monomer The vinyl chloride-based monomer used in the method of the present invention includes vinyl chloride monomer alone and a mixture of copolymerizable monomers mainly composed of vinyl chloride monomer. As the other monomer copolymerizable with the vinyl chloride monomer, those generally used in the related art can be used and are not particularly limited. Examples of the above-mentioned other monomers include vinyl acetates such as vinyl acetate, vinyl propionate and vinyl stearate, alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, octyl vinyl ether, lauryl vinyl ether and cetyl vinyl ether, ethylene and the like. Α-olefins, acrylic acid,
Mono-unsaturated acids such as methacrylic acid, alkyl esters of these mono-unsaturated acids such as methyl ester and ethyl ester, di-unsaturated acids such as maleic acid, fumaric acid, itaconic acid, etc. One or a mixture of two or more of alkyl esters such as methyl ester and ethyl ester of saturated acid, vinylidene compound such as vinylidene chloride, unsaturated nitrile such as acrylonitrile and the like can be mentioned. These other monomers are usually 3
It is used in an amount of 0% by weight or less, preferably 20% by weight or less, but there is no particular limitation.

Dispersant The dispersant that can be used in the method of the present invention is not particularly limited, and may be one that has been commonly used in the suspension polymerization method of vinyl chloride monomers. Examples of the dispersant include partially saponified polyvinyl acetate (so-called polyvinyl alcohol), cellulose derivatives such as hydroxypropylmethyl cellulose, and water-soluble polymers such as gelatin. In addition, anionic surfactants such as sodium lauryl sulfate and nonionic surfactants such as sorbitan fatty acid esters and glycerin fatty acid esters may be used as a dispersion aid. These dispersants or dispersion aids can be used alone or in combination of two or more. The amount of these dispersants used is not particularly limited, and its type, stirring strength, polymerization temperature,
Depending on the type and composition of other monomers to be copolymerized with the vinyl chloride monomer and the particle size of the intended vinyl chloride polymer, etc. 0.001-2% by weight, preferably 0.03-1
Used in the range of wt%.

Emulsifiers Examples of emulsifiers used in the emulsion polymerization method and the fine suspension polymerization method include higher alcohol sulfate ester salts (alkali metal salts and ammonium salts), alkylbenzene sulfonates (alkali metal salts and ammonium salts), higher salts. Examples include fatty acid salts (alkali metal salts, ammonium salts) and other anionic surfactants, nonionic surfactants, and / or cationic surfactants. These surfactants may be used alone or in combination of two or more. The amount of the emulsifier used is usually 0.1 to 3% by weight (preferably 0.3 to 1% by weight) based on the vinyl chloride-based monomer, but is not particularly limited. Further, these emulsifiers may be additionally used for adjusting the foaming property during processing, and at this time, separately from the emulsifier for polymerization, they may be added after the completion of the polymerization reaction.

Polymerization Initiator The polymerization initiator used in the method of the present invention may be any conventionally used one in each polymerization method of vinyl chloride type monomers and is not particularly limited.

The polymerization initiator used in the suspension polymerization method is, for example, t-butylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-hexylperoxyneodecanoate, Perester compounds such as α-cumyl peroxy neodecanoate, diacyl or dialkyl peroxide compounds such as dilauroyl peroxide, percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, azobis (2,4 -Dimethylvaleronitrile), azo compounds such as azobisisobutyronitrile, and the like. These polymerization initiators can be used alone or in combination of two or more. Although the amount of the polymerization initiator used varies depending on the type of the initiator, the polymerization temperature, the desired reaction time, etc., it is generally in the range of 0.01 to 1% by weight based on the total amount of the vinyl chloride monomer. As the polymerization initiator used in the emulsion polymerization method, persulfate (sodium salt,
Water-soluble peroxides such as potassium salt, ammonium salt) and hydrogen peroxide, or water-soluble peroxides and water-soluble reducing agents (for example, sodium sulfite, sodium pyrosulfite, sodium hydrogen sulfite, ascorbic acid, sodium). Examples of the water-soluble redox initiator include a combination with formaldehyde sulfoxylate and the like).

The polymerization initiator used in the fine suspension polymerization method is azobisisobutyronitrile or azobis (2,4-
Dimethyl valeronitrile), lauroyl peroxide,
Examples thereof include a monomer-soluble (oil-soluble) initiator such as t-butylperoxypivalate, or a redox-based initiator composed of a combination of these oil-soluble initiators and the above water-soluble reducing agent.

Other Auxiliary Agents Further, in the method of the present invention, a polymerization degree adjusting agent (a chain transfer agent, a chain transfer agent, or
Cross-linking agent), antioxidant, pH adjuster, various polymerization aids such as activators of redox-based initiators can be added as appropriate. The general conditions used for body polymerization can be used.

As the polymerization degree regulator used for the polymerization of vinyl chloride type monomers, trichlorethylene, carbon tetrachloride, chain transfer agents such as 2-mercaptoethanol and octyl mercaptan, diallyl phthalate and triallyl isocyanurate. Examples thereof include cross-linking agents such as ethylene glycol diacrylate and trimethylolpropane trimethacrylate.

<Polymerization Method> Preparation Method In carrying out the method of the present invention, an aqueous medium to be filled in a vessel,
The charging ratio and charging method of the vinyl chloride monomer, the polymerization initiator, the dispersant of the suspension polymerization method, the emulsifier of the emulsion polymerization method and the fine suspension polymerization method, and other various polymerization aids are not particularly limited.

Polymerization temperature : The polymerization temperature employed in the method of the present invention includes the type of polymerization initiator used, the polymerization method, the presence or absence of a polymerization degree modifier,
Generally, it varies from 0 to, although it varies depending on the target degree of polymerization and the like.
90 ° C., especially 40 to 70 ° C. is often used.
Further, in the reaction, even if the polymerization is carried out at a constant temperature,
Alternatively, the polymerization temperature may be changed during the polymerization.

Polymerization Termination Method In the method of the present invention, examples of the method for terminating the polymerization reaction include a method of adding a so-called polymerization inhibitor or a polymerization terminator, a method of recovering unreacted monomers from a polymerization tank, and the like. .

<Post-Treatment Method> The operations such as dehydration and drying of the slurry of the vinyl chloride polymer produced by the suspension polymerization method are generally performed such as centrifugal dehydration and fluidized drying.
Drying means may be used without any particular limitation. Operations such as drying of the latex of the vinyl chloride polymer produced by the emulsion polymerization method and the fine suspension polymerization method can be performed by spray drying using a conventionally used rotating disk or a spray nozzle such as a two-fluid nozzle. Means may be used and there is no particular limitation. Also, before the drying treatment, some of the water content in the latex is removed in advance,
A concentration operation for increasing the concentration of the vinyl chloride polymer in the latex may be performed, or a product after drying may be classified and pulverized.

[0040]

EXAMPLES Next, specific embodiments of the method of the present invention will be described with reference to Examples, but the present invention is not limited as long as the gist thereof is not exceeded.
The present invention is not limited to the examples below. In addition,
The fish eye of the obtained vinyl chloride polymer (hereinafter,
“FE” is abbreviated) is evaluated by the following method,
It was judged that the smaller the number of FE, the higher the quality of the vinyl chloride polymer.

Fish eye evaluation method 100 parts by weight of vinyl chloride polymer, plasticizer (DOP) 5
0 parts by weight and 3 parts by weight of a lead-based powder stabilizer were sampled on the basis of 100 g of a vinyl chloride polymer, premixed in a beaker, and then kneaded with a roll at 155 ° C. for 4 minutes, 5 minutes, and 7 minutes, respectively, A roll sheet having a thickness of 0.4 mm was created. The number of FEs observed in a square (area: 25 cm ² ) having a side of 5 cm on each side of the obtained roll sheet was counted to obtain the FE number.

<Example 1> An internal volume of 400 liters was provided with a stirrer, and the inner wall of the tank (and the surface of the inner cylinder of the temperature control element) was electrolytically polished to have a Rmax of about 1.2 μm. The bottom temperature control element as shown in FIG. 3 and the communicating pipe as shown in FIG. 1 were installed in the stainless steel temperature control element type vessel container divided into.

In this tank container, vinyl chloride monomer 100 k
g, 150 kg of deionized water, 60 g of partially saponified polyvinyl acetate as a dispersant, and 40 g of dioctyl peroxydicarbonate as an initiator, and then warm water is circulated through the temperature control element to heat up to 57 ° C. to start polymerization. did. After carrying out the polymerization while maintaining the reaction temperature of 57 ° C until the predetermined polymerization rate is reached, the unreacted vinyl chloride monomer is recovered, the produced slurry is extracted, ventilated, and the tank container is opened to open the tank. The state of scale adhesion to the inner wall of the container (welded part, other parts, lower part of the temperature control element lower end partition wall) was observed.

After observing the scale adhesion state, the inner wall of the vessel was washed with low-pressure ion-exchanged water, and the test of the next batch was repeated under the same conditions. Table 1 shows the results of observation of the scale adhesion state. The vinyl chloride polymer obtained by drying the slurry obtained in each batch was evaluated for FE by the method described above. Table 2 shows the results.

Comparative Example 1 Vinyl chloride monomer was used under the same conditions as in Example 1 except that a temperature control element type tank container having no bottom temperature control element as shown in FIG. 5 was used as the tank container. Polymerization reaction was performed and the same evaluation was performed. The results are also shown in Table-1 and Table-2.

[0046]

[Table 1] Criteria: ○ ... Adhesion is generated on the inner wall of less than 10% of the total surface area. △ ... Adhesion is generated on the inner wall of 10% or more and less than 50% of the total surface area .. × Adhesion is generated on the inner wall of 50% or more of the total surface area.

[0047]

[Table 2]

[0048]

[Effects of the Invention] When polymerizing a vinyl chloride monomer using a temperature control element type tank container, the bottom end plate portion of the container body is connected to the temperature control element of the body of the tank container body. By adopting the method of the present invention in which the temperature control element having a shape inclined toward the center of the bottom of the tank container is used, (1) heat removal efficiency is high and productivity is good, and welding line Maintaining and securing the effect of using a temperature control element type polymerization tank, which is less exposed and the quality of the product polymer is good, and (2) for the lower end of the temperature control element and / or the partition wall and bottom end plate for fixing this Since there is no space between them, the risk of scale adhesion and corrosion at this part is reduced, so that the product quality is improved and the maintenance of the equipment is facilitated.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a temperature control element type vessel container that can be used for carrying out the method of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a longitudinal cross-sectional view of a main part showing another example of a temperature control element type tank container that can be used for carrying out the method of the present invention.

FIG. 4 is a vertical cross-sectional view of a main part showing another example of a temperature control element type tank container that can be used for carrying out the method of the present invention.

FIG. 5 is a longitudinal sectional view showing an example of a temperature control element type tank container outside the scope of the method of the present invention.

FIG. 6 is a vertical sectional view showing an example of a conventional tank container.

FIG. 7 is an enlarged vertical sectional view of an essential part showing another example of a conventional tank container.

[Explanation of symbols]

1, 1'Container main body 2 Straight body part 3 Bottom mirror plate 4 Top mirror plate 5 Temperature control element (5a, 5b, 5c Bottom temperature control element) 6 Inner plate 7, 17 Partition plate 8 Outer strip 9, 19 Heat transfer channel 10 Heat medium flow path inlet 11 Heat medium flow path outlet 12 Tank container nozzle 13 Partition wall 14 Gap chamber 15 Communication pipe 16 (External) jacket 18 Inner strip H Gap

Claims (6)

[Claims] 1. Polymerization of vinyl chloride or a mixture of vinyl chloride-based copolymerizable monomers in an aqueous medium is carried out by arranging partition plates side by side at right angles to the outer surface of the inner plate, A flow path wall (hereinafter referred to as a "temperature control element") having a flow path of a heat medium partitioned by the partition plate between the inner plate and the outer strip by straddling an outer strip between the ends of the partition plate. When the temperature control element is formed in a tank container in which the outer strip side is opposed to the inner surface of the container body and fixed at a distance, the temperature control element of the cylindrical body of the tank container body is formed. A method for producing a vinyl chloride polymer, characterized in that a tank container in which a temperature control element having a shape inclined toward the center of the bottom of the tank container is provided on the bottom end plate portion of the tank container body is used. 2. The method for producing a vinyl chloride polymer according to claim 1, wherein the temperature control element provided on the bottom end plate portion of the tank container body has a conical shape or a truncated cone shape. 3. The method for producing a vinyl chloride polymer according to claim 1, wherein the temperature control element provided on the bottom end plate portion of the tank container body has a dish shape. 4. The method for producing a vinyl chloride polymer according to claim 1, wherein the temperature control element provided on the bottom end plate portion of the tank container body has a hemispherical shape. 5. The method for producing a vinyl chloride polymer according to claim 1, wherein the temperature control element has a shape similar to that of the bottom end plate of the tank container. 6. A structure having a gap chamber formed by sealing the upper and lower portions of the gap between the outer strip side of the temperature control element and the inner surface of the tank container body, and the inner surface of the tank container body and the temperature The tank container in which the space surrounded by the inner plate of the adjusting element and the gap chamber have substantially the same pressure is used.
Item 8. A method for producing a vinyl chloride polymer according to the item.