JPH08337605A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE: To produce a vinyl chloride polymer while inhibiting the deposition of polymer scales by performing the reaction while feeding the liquid through a clearance room into the reactor body in a tank having an exit for the liquid on the top of the room and at the position opposite to an inlet of the liquid. CONSTITUTION: A tank having a clearance room 14 formed by fixing the top and bottom of a temperature-controlling element with a partition 13 or the like, the body of the tank 1, a communicating vessel 15 through which the room 14 communicates with the body 1, an exit for the liquid secured at the position opposite to an inlet 17 and an electropolished inside wall is used. From the liquid inlet 17 of the tank, water, a vinyl chloride monomer, about 0.001-2wt.%, based on the monomer, dispersant such as partially saponified polyvinyl acetate, about 0.01-1wt.%, based on the monomer, initiator such as dioctyl peroxydicarbonate and other adjuvants are fed into the tank, and the reaction mixture is polymerized by heating to about 40-70 deg.C by circulating warm water through the temperature-controlling element. When a specified conversion is reached, unreacted vinyl chloride monomer is recovered, and the formed slurry is withdrawn through a nozzle 12 and dried to obtain a high- quality vinyl chloride polymer.

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, vinyl chloride or a mixture of vinyl chloride-based copolymerizable monomers (collectively,
For the polymerization reaction of vinyl chloride-based monomer), the container body 1'is formed of a pressure-resistant closed container in which dish-shaped end plates are welded to both ends of the cylindrical body, and to remove heat or heat the contents. An outer jacket type tank container (FIG. 7) is used in which the jacket 18 is attached to the outside of the container body.

In this type of tank container, since the container body maintains the 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 is an exothermic reaction. It was difficult to obtain high productivity in the polymerization of. Further, in the case of enlarging the tank container, it is necessary to increase the plate thickness of the wall of the container main body from the viewpoint of strength, and there is a disadvantage that the heat transfer coefficient is further lowered.

Therefore, in order to solve this inconvenience in heat conduction, partition plates 19 are arranged side by side at a right angle to the inner surface of the container body 1 ', as shown in FIG. An internal jacket method in which a spiral flow path 21 partitioned by a partition plate is formed between the inner strip 20 and the inner surface of the container body by straddling the inner strip 20 (JP-A-57-147502). The tank container of is proposed.
In the tank container of this method, the pressure resistance strength can be increased by making the interval between the partition plates smaller than the inner diameter of the container body, the wall thickness of the inner strip can be reduced, and the heat transfer coefficient can be increased.

However, while the inner jacket type tank container has excellent thermal conductivity, the inner surface of the tank container where the contents come into contact with the vinyl chloride monomer during the polymerization reaction has a large number of welded portions between inner strips on the surface. There is a disadvantage due to being exposed. 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 roughness of the contacting portion of the reaction mixture (hereinafter referred to as the liquid contacting portion). If it is rough, polymer scale is likely to adhere, and if the generated scale peels and mixes into the product, the quality deteriorates (especially unmelted material remains in the film when processed into a film, so-called fish eye ( Cause FE)). In addition, when trying to prevent the adhesion of polymer scale that causes quality deterioration, it is necessary to extremely smooth the existing welding lines and to introduce special adhesion prevention / removal technology. There is an inconvenience that the cost increases.

Further, in the polymerization reaction of vinyl chloride-based monomer, stainless steel is usually used as the material of the inner surface of the tank because of the corrosiveness caused by hydrogen chloride generated as the reaction proceeds. Indicates that residual stress due to welding is concentrated, and when a vinyl chloride monomer polymerization reaction is performed using an internal jacket type tank container in which many welding lines are adjacent to the inner surface of the container, the reaction progresses. There is a concern of stress corrosion cracking due to the accompanying hydrogen chloride (chlorine ion). Therefore, it is necessary to carefully and continuously perform the inspection of the degree of deterioration of the welding line, and there is also a disadvantage that the maintenance is complicated and the inspection cost increases.

In order to solve the inconvenience while taking advantage of the advantage of this inner jacket type tank container, the present inventors have previously described, as a method for producing a vinyl chloride-based polymer in an aqueous medium without such a problem, Partition plates are arranged side by side at a right angle to the outer surface of the cylinder, and an outer strip is laid between the ends of the partition plate so that the heat separated by the partition plate between the inner cylinder and the outer strip. A flow path wall (hereinafter referred to as a temperature control element) having a flow path for the medium is formed, and the temperature control element is fixed in the container body with an outer strip side facing the inner surface of the container body with a space therebetween. In a tank container having a structure in which upper and lower parts of a gap between the outer strip side of the temperature control element and the inner surface of the container body are sealed to form a gap chamber (hereinafter referred to as a temperature control element type tank container), Internal pressure of the void chamber and container Body inner surface and surrounded by the inner cylinder of the temperature control element space (hereinafter, referred to body chamber) while keeping small the difference communicating pipe or the like with the internal pressure of, proposed a method of performing a polymerization reaction.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to manufacture a vinyl chloride polymer in a temperature control element type tank container having a structure having a main chamber and a gap chamber. By reducing the generation and adhesion of scale in the phase part,
It is an object of the present invention to provide a method capable of producing a high-quality vinyl chloride polymer with high productivity.

[0009]

That is, the gist of the present invention is as follows.
Polymerization of vinyl chloride or a mixture of copolymerizable monomers mainly composed of vinyl chloride in an aqueous medium is performed by arranging partition plates side by side at right angles to the outer surface of the inner cylinder, and between the tip ends of the partition plates. By straddling an outer strip on the inner wall, a flow path wall (temperature control element) having a flow path for a heat medium partitioned by a partition plate is formed between the inner cylinder and the outer strip. In the container body, the outer strip side is fixed to the inner surface of the container body so as to be spaced apart, and the upper and lower portions of the gap between the outer strip side of the temperature control element and the inner surface of the container body are sealed by partition walls. Has a structure in which a gap chamber is formed, and the body chamber surrounded by the inner surface of the container main body and the inner cylinder of the temperature control element and the gap chamber are provided in a communication pipe or the partition wall (hereinafter referred to as a communication part). A tank that communicates with each other In the vessel, when the liquid is supplied to the main body chamber through the gap chamber, the liquid outlet from the gap chamber is provided in the upper part of the gap chamber and at a position symmetrical to the liquid inlet. A method for producing a vinyl chloride-based polymer, characterized by using a container.

Hereinafter, the present invention will be described in detail. <Bath container> Bath container main body The temperature control element type bath container used in the method of the present invention has the following structure. That is, as shown in FIGS. 1 to 3, the partition plates 7 are arranged side by side at right angles to the outer surface of the inner cylinder 6, and the outer strips 8 are straddled between the tips of the partition plates, whereby A temperature control element 5 having a heat medium passage 9 partitioned by a partition plate is formed between the cylinder and the outer strip. The outer diameter of the temperature control element is made smaller than the inner diameter of the tank container, and the outer strip side of the temperature control element is fixed to the inner surface of the container body 1 with a space therebetween.

The temperature control element is preferably fixed so that its central axis and the central axis of the container substantially coincide with each other.
At this time, a gap corresponding to the difference in diameter between the inner surface of the container body and the outer surface of the temperature control element (that is, the outer strip side) is formed, which is substantially uniform in the circumferential direction. The lower end of the 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. 1, or may be sealed via a partition wall.

The upper end of the temperature control element is shown in FIG.
The partition wall 13 may be attached and sealed to the cylindrical body portion 2 of the container as shown in FIG. 2, or the partition wall 13 may be attached and sealed to the top end plate 4 as shown in FIG. 1 or 4. In this way, a gap chamber is formed between the outer surface of the temperature control element fixed inside the container body and the inner surface of the container body. As a result, it is possible to prevent the reaction mixture from penetrating into the gap and the scale from adhering and growing.

It is preferable that the partition wall or the like for sealing the upper part and / or the lower part of the gap is provided with an expansion / contraction absorbing part capable of absorbing expansion / contraction of the temperature control element due to heat. It is necessary to have a strength that can withstand the temperature and pressure normally used during the polymerization of the system monomer. 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 reaction pressure or the like, the inner surface of the container body (usually,
For safety, it is preferable to minimize the difference between the internal pressure of the space (main body chamber) surrounded by the top end plate and bottom end plate) and the inner cylinder of the temperature control element and the internal pressure of the gap chamber. The pressure resistance of the partition walls is not necessary.

In the method of the present invention, as a method for reducing the difference between the internal pressure of the main body chamber and the internal pressure of the interstitial chamber, the main chamber and the interstitial chamber are connected, for example, to the communicating pipe 15 or a pressure equalizer as shown in FIG. Method of connecting with piping (equalizing pressure piping) via
Alternatively, as shown in FIG. 5, a method of providing an opening (communication port 16) in a partition wall for fixing the temperature control element is used.
Further, by providing the liquid inlet 17 in the gap chamber and supplying the liquid into the main body chamber through the communication pipe or the communication port,
To prevent the blockage of the communication pipe and the communication port due to the generation and adhesion of scales in the communication pipe or the communication port and their surroundings, and to prevent the entry of vinyl chloride vapor or polymerization mixture into the gap chamber. However, since the partition wall (upper partition wall when partition walls are provided above and below the temperature control element) does not have a flow path for a heat medium, cooling cannot be performed, and this part is heated by reaction heat to partition the partition wall. Polymerization of vinyl chloride-based monomers may occur on the surface of the main body chamber of the product, or scattered polymer particles may adhere to the scale, which may adversely affect the quality of the product polymer. There is.

Therefore, in the method of the present invention, the outlet of the liquid from the gap chamber, that is, the opening or the communication port of the communication tube on the gap chamber side (hereinafter collectively referred to as the communication opening) is the upper part of the gap chamber, Further, as shown in FIG. 1 and FIG. 6 which is a sectional view thereof, by providing the liquid inlet 17 to the gap chamber at a position symmetrical to the liquid inlet 17, the distance between the liquid inlet and the liquid outlet is increased and the liquid inside the gap chamber is separated. Prevents "short pass" and reduces liquid retention in the void chamber. In this case, as shown in FIG. 3, if the liquid inlet is provided in the lower part of the gap chamber and the communication opening is provided in the uppermost part of the gap chamber, there is no liquid remaining in the gap chamber above the communication opening. , More preferred.

Further, in order to further reduce the retention of the liquid in the portion corresponding to the upper partition wall, as shown in FIG. 4, the liquid inlets of the gap chambers are provided in the upper portions of the gap chambers in directions symmetrical to the communication openings. It is also a preferred embodiment to provide it at two places (17a, 17b) in the lower part.

In the method of the present invention, the position symmetrical to the inlet of the liquid means the cross section (plan view) of the tank container as shown in FIG.
Above, an angle of 0 to ± 45 °, preferably 0 to ± 30 ° from the center of the tank container with respect to the extension direction of the straight line connecting the central axis of the tank container and the liquid inlet (the angle is in the extending direction of the straight line). It refers to the wall of the vessel container in the direction of 0 ° for overlapping. This position does not necessarily have to be flush with the liquid inlet. Further, the central axis of the tank container means the central axis of the cylinder when the tank container is considered to have a shape in which mirror plates are provided above and below the cylindrical body.

The communication opening is symmetrical with the liquid inlet,
If it is not provided in the upper part of the gap chamber, the liquid to be supplied tends to stay in the upper part of the gap chamber, the liquid in this part is heated, and the temperature of the partition wall rises as a result, and the adhesion in this part occurs. May cause generation. When the communication pipe is used, the opening on the main chamber side of the communication pipe is provided in the top end plate, the body, etc., but as shown in FIG. 3, this communication pipe may penetrate the tank container.

The liquid to be supplied is preferably of the same quality as water used as a medium for the polymerization reaction,
For example, deionized water may be used, but it is not particularly limited as long as it does not adversely affect the quality of the vinyl chloride polymer. The amount of liquid supplied is not particularly limited as long as it does not adversely affect the polymerization reaction and quality and there is no adverse effect due to overfilling, etc., but also the amount of liquid supplied from other parts to the main chamber It is preferable that the total amount of the liquid does not exceed the volume contraction amount due to the polymerization of the vinyl chloride-based monomer.

It is preferable to supply the liquid continuously or intermittently at least during the polymerization reaction period. The flow path of the heat medium in the temperature control element may be a single spiral as shown in FIG. 1, or may be divided into a plurality of spiral, meandering, etc. flow paths, and is not particularly limited. Not done. Further, as the heat medium flowing in the flow path, steam, hot water, etc. are used for heating, room temperature water such as industrial water for cooling, water cooled by a separate refrigerator, refrigerant such as ethylene glycol, CFCs, etc. The low-temperature boiling point refrigerant can be used, but is not particularly limited.

The plate thickness of the inner cylinder depends on the required strength and the space between the partition plates, but since the space between the partition plates is smaller than the body length of the container body, the plate thickness of the inner cylinder should be reduced. Therefore, a high heat transfer coefficient can be obtained. As described above, the material of the inner cylinder is made of stainless steel (solid stainless steel, stainless steel / carbon steel clad material, especially SUS316L) in consideration of the corrosion resistance of the portion in contact with the reaction mixture of vinyl chloride-based monomers.
Is preferable) or a glass lining material is used,
The material is not particularly limited as long as it is a material that is resistant to stress corrosion cracking due to chlorine ions. From the viewpoint of preventing scale adhesion, the surface of the inner cylinder is preferably smooth, and as a method for smoothing the surface, methods such as buffing and electrolytic polishing which are usually carried out industrially can be used.
There is no particular limitation. As the surface roughness, the maximum height Ry is usually 10 μm or less, preferably 3 μm or less,
More preferably, it is 1 μm or less. Ry is measured by JI
The method specified in S B 0601 may be used.

Since the proportion of the welded portion on the inner surface of the main body chamber side of the tank container manufactured in this way is significantly smaller than that of the internal jacket type tank container, the adhesion and formation of polymer scale is small and the product obtained is The quality is also good,
Since 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 tank container.

The shape of the stirring blades, baffles, etc., which are the auxiliary equipment of the tank container incidental equipment and other tank containers (hereinafter sometimes referred to as a polymerization tank), is not particularly limited, and the conventional suspension polymerization method, In the emulsion polymerization method or the fine suspension polymerization method, generally used facilities and equipment can be used. Further, a reflux condenser may be provided outside the gas phase portion of the polymerization tank.

<Polymerization prescription> The vinyl chloride-based polymer referred to in the present invention is a polymer having vinyl chloride as a main constituent unit, which is obtained by polymerizing a vinyl chloride-based monomer in an aqueous medium. Say. Further, the polymerization reaction period according to the present invention, after the reaction system reaches a predetermined polymerization temperature, the internal pressure of the polymerization tank is reduced by a predetermined pressure from the saturated pressure of the vinyl chloride-based monomer at the temperature of the reaction system, It refers to the time until the collection of unreacted monomers begins.

Polymerization methods of vinyl chloride type monomers in an aqueous medium generally include suspension polymerization method, emulsion polymerization method and fine suspension polymerization method. Suspension polymerization of a vinyl chloride monomer is usually carried out by polymerizing a vinyl chloride 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.

Monomers The vinyl chloride monomers used in the method of the present invention include vinyl chloride monomers alone and a mixture of copolymerizable monomers mainly composed of vinyl chloride monomers. 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 conventionally used generally in the suspension polymerization method of vinyl chloride-based 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 sulfuric acid 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 foamability 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 is not particularly limited and may be one that has been generally used conventionally in each polymerization method of vinyl chloride type monomers. Examples of the polymerization initiator used in the suspension polymerization method include t-butylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-hexylperoxyneodecanoate and α-quan. Perester compounds such as milperoxy neodecanoate, diacyl or dialkyl peroxide compounds such as dilauroyl peroxide, diisopropyl peroxydicarbonate, di-2
Examples include percarbonate compounds such as ethylhexyl peroxydicarbonate, azo compounds such as azobis (2,4-dimethylvaleronitrile) and azobisisobutyronitrile. 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.

The polymerization initiator used in the emulsion polymerization method is a water-soluble peroxide such as persulfate (sodium salt, potassium salt, ammonium salt), hydrogen peroxide, or the like, or a water-soluble peroxide thereof. Examples of the water-soluble redox-based initiators include a combination of a water-soluble reducing agent (eg, sodium sulfite, sodium pyrosulfite, sodium bisulfite, ascorbic acid, sodium formaldehyde sulfoxylate, etc.).

As the polymerization initiator used in the fine suspension polymerization method, azobisisobutyronitrile, azobis (2,
4-dimethylvaleronitrile), lauroyl peroxide, t-butylperoxypivalate and other monomer-soluble (oil-soluble) initiators, or a redox comprising a combination of these oil-soluble initiators and the aforementioned water-soluble reducing agent. An example is a system initiator.

Other auxiliaries Further, in the method of the present invention, a polymerization degree adjusting agent (chain transfer agent, cross-linking agent), antioxidant, pH used in the polymerization of vinyl chloride-based monomer may be added, if necessary. Various polymerization aids such as regulators and activators of redox type initiators can be appropriately added, and the charging amount of each of these components is generally the same as that conventionally used for polymerization of vinyl chloride monomers. It does not matter under normal conditions.

As the degree-of-polymerization regulator used for the polymerization of vinyl chloride-based 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 When carrying out the method of the present invention, an aqueous medium to be added to the tank container,
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 the polymerization tank, and the like. .

<Post-Treatment Method> Operations such as dehydration / drying of the slurry of the vinyl chloride polymer produced by the suspension polymerization method are generally performed such as centrifugal dehydration / fluid 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 without any particular limitation. Before the drying treatment, part of the water content in the latex may be removed in advance to increase the concentration of the vinyl chloride polymer in the latex, or the concentration operation may be performed. You can go.

[0039]

EXAMPLES Next, specific embodiments of the method of the present invention will be described with reference to Examples. However, in the present invention, the physical properties of the obtained vinyl chloride polymer are evaluated by the following physical property measuring methods. It was 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. Unmelted particles (FE) found in a square of 5 cm on each side (area 25 cm ² ) of the obtained roll sheet.
Were counted and used as the FE number.

<Example 1> An internal volume of 400 liters was provided with a stirrer, and the inner wall of the vessel (that is, the surface of the inner cylinder of the temperature control element) was electropolished to about Ry 1.2 μm.
As shown in FIG. 1, a communication pipe and a liquid inlet were installed in a stainless steel temperature control element type vessel container divided into a gap chamber and a main chamber.

Vinyl chloride monomer 100 k was added to this tank container.
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. From the start of the polymerization reaction (the polymerization reaction is started when the internal temperature of the polymerization tank reaches a predetermined reaction temperature) to the end of the recovery of the unreacted vinyl chloride monomer, Deionized water was supplied from the charging pipe into the tank container body by a plunger pump at a flow rate of 2.5 liter / hr.

Polymerization was carried out while maintaining a reaction temperature of 57 ° C. until a predetermined polymerization rate was reached. Then, unreacted vinyl chloride monomer was recovered, the produced slurry was extracted, ventilated, and the tank container was opened to observe the scale adhesion state to the partition wall above the temperature control element. After observing the scale adhesion state, the inner wall of the tank container 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 in each batch was evaluated for physical properties by the methods described above. Table 2 shows the results.

<Comparative Example 1> FIG. 9 shows the communication pipe and the liquid inlet.
Polymerization reaction of vinyl chloride monomer was carried out under the same conditions as in Example 1 except that a temperature control element type polymerization tank installed on the same side of the polymerization tank was used as shown in FIG. . The results are also shown in Table-1 and Table-2.

[0044]

[Table 1] ^* : The half-circumference centering on the communication opening of the partition wall is defined as the "partition wall communication opening side", and the remaining half circumference part is defined as the "opposite side of the partition communication opening".

Criteria: ○ 1 of the surface area of the partition wall
Adhesion is formed on the inner wall of less than 0%. △ ... Adhesion is formed on the inner wall of 10% or more and less than 50% of the partition wall surface. × ... Adhesion is formed on the inner wall of 50% or more of the surface area of partition wall.

[0046]

[Table 2]

[0047]

EFFECTS OF THE INVENTION In a temperature control element type tank container,
The upper and lower parts of the gap between the element and the container body are sealed by partition walls or the like to form a gap chamber, and by connecting this gap chamber and the inside of the tank container body, the internal pressure of the gap chamber and the internal pressure of the container body And the outlet of the liquid from the interstitial chamber is provided in the upper part of the interstitial chamber and at a position symmetrical to the inlet of the liquid, and through the outlet of the liquid into the tank container body during the polymerization period. By adopting the method of the present invention in which a liquid is supplied, it is possible to prevent the generation and growth of scale in the upper partition wall and to produce a high-quality vinyl chloride polymer.

[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 sectional view 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 showing another example of a temperature control element type vessel container that can be used for carrying out the method of the present invention.

FIG. 5 is a vertical cross-sectional view 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. 6 is a cross-sectional view taken along the line A-A ′ of the tank container shown in FIG. 1.

FIG. 7 is a vertical sectional view showing an example of a conventional tank container.

FIG. 8 is an enlarged vertical sectional view of an essential part showing an example of a conventional tank container.

FIG. 9 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.

[Explanation of symbols]

 1, 1'Container body 2 Cylindrical body 3 Bottom mirror plate 4 Top mirror plate 5 Temperature control element 6 Inner cylinder 7 Partition plate 8 Outer strip 9 Heat medium flow passage 10 Heat medium flow passage inlet 11 Heat medium flow passage outlet 12 Tank container Nozzle 13 Partition wall 14 Gap chamber 15 Communication pipe 16 Communication port 17, 17a, 17b Liquid inlet 18 (External) jacket 19 Partition plate 20 Inner strip 21 Heat medium flow passage H Gap

Claims (3)

[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 cylinder. A flow path wall (hereinafter referred to as a temperature control element) having a flow path for a heat medium partitioned by the partition plate is provided between the inner cylinder and the outer strip by straddling an outer strip between the ends of the partition plate. This temperature control element is fixed in the container body with the outer strip side facing the inner surface of the container body with a space between the outer strip side of the temperature control element and the inner surface of the container body. It has a structure in which the upper and lower parts are sealed by partition walls to form a gap chamber, and the space surrounded by the inner surface of the container body and the inner cylinder of the temperature control element (hereinafter referred to as the body chamber) and the gap chamber are Opening provided in the communication pipe or the above partition When the liquid is supplied to the main body chamber through the interstitial chamber in the tank container communicated by the mouth (hereinafter referred to as the communication port), the outlet of the liquid from the interstitial chamber is located above the interstitial chamber. A method for producing a vinyl chloride-based polymer, characterized in that a tank container provided at a position symmetrical to the liquid inlet is used. 2. The method for producing a vinyl chloride polymer according to claim 1, wherein a tank container provided with a liquid inlet to the interstitial chamber at a lower portion of the interstitial chamber is used. 3. The method for producing a vinyl chloride polymer according to claim 1, wherein a tank container is provided in which at least two inlets for the liquid to the void chamber are provided in the lower portion and the upper portion of the void chamber.