JPH09110905A - Production of vinyl chloride polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a process for producing a vinyl chloride polymer wherein a scaling-preventive coating soln. can be applied uniformly in a polymerizer even when the polymerizer has a lage size or a complicated structure. SOLUTION: In a process for producing a vinyl chloride polymer by the suspension polymn. of vinyl chloride or a mixture manily comprising vinyl chloride in a polymerizer, a scaling-preventive coating film is formed on the part to be brought into contact with the monomer component in the polymerizer by spraying a scaling-preventive coating soln. while controlling the sizes of liq. drops to 100-300μm.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for producing a vinyl chloride polymer.

[0002]

2. Description of the Related Art Generally, when a vinyl chloride monomer is polymerized in an aqueous medium, a so-called "scale" adheres to the inner wall of a polymerization vessel which the monomer contacts during the polymerization. When continuous operation is performed using a polymerization vessel to which this scale is attached, the scale is mixed in the obtained polymer, which causes a problem that fish eyes increase in the processed product of the polymer. Also, when scale adheres to the polymerization container,
Since the heat transfer performance of the polymerization container deteriorates, it is difficult to maintain the polymerization temperature at a predetermined temperature. Therefore, it is necessary to regularly remove the scale adhering to the inside of the polymerization vessel, but the removal work is complicated, and the polymerization cycle becomes long, resulting in a marked decrease in polymer productivity. In particular, when a large-sized polymerization container is used to improve the productivity, the removal operation takes a longer time, and therefore the polymerization cycle is greatly affected. Further, in recent years, in order to shorten the polymerization time and increase the productivity of the polymer, a plurality of cooling baffles are provided in the polymerization container. Therefore, the structure inside the polymerization vessel becomes complicated, and the scale removal work becomes more difficult.

Conventionally, for the purpose of preventing the scale from adhering to the inner wall of the polymerization container, a scale anti-sticking agent coating liquid is applied to the inner wall of the polymerization container, etc., and dried to prevent the scale from adhering to scale. There is known a method of forming the. As a method of applying the scale anti-adhesion agent coating liquid, a method of spraying the scale anti-adhesion agent coating liquid from a nozzle installed in the gas phase portion of the polymerization container is generally adopted. As a specific example of such a method, there is a method of spraying a scale anti-sticking agent coating liquid from a one-fluid nozzle (JP-A-56-61001).
JP-A-4-252201), a method of spraying a scale anti-sticking agent coating liquid with a carrier gas such as air or propane from a two-fluid nozzle (see JP-A-56-500177), and the like. . However, in the conventional method using the one-fluid nozzle, the spraying pressure of the scale-adhesion-preventing agent coating liquid is 10 kg / cm ² or less, so that the particle diameter of the spray droplets of the scale-adhesion-preventing agent coating liquid is 500 μm or more. . Therefore,
When a polymerization container having a complicated internal structure, for example, a polymerization container having a plurality of cooling baffles as described above is used, the scale anti-sticking agent coating solution is uniformly applied to all the portions in contact with the vinyl chloride monomer. Is difficult. In particular, it is extremely difficult to apply it to a gap between a structure such as a cooling baffle provided in the polymerization container and the inner wall of the polymerization container, or the back surface. Further, if an attempt is made to uniformly apply such a gap or back surface, it is not industrial because it requires an extremely large amount of scale anti-sticking agent, and the coating time of the scale anti-sticking agent coating liquid becomes long. There is also a drawback that the polymerization cycle is lengthened and the productivity is lowered. Therefore, in the conventional method using the one-fluid nozzle, it is the current situation that the above-mentioned gap or the back surface is not substantially coated,
There is a drawback in that the scale attached to such a place causes the above problems.

Further, in the conventional method using the two-fluid nozzle, the spray pressure of the scale anti-sticking agent coating liquid is 100 kg / c.
Since it exceeds m ² , the particle size of the sprayed droplets of the scale anti-sticking agent coating liquid is 50 μm or less. Even when the sprayed droplets become mist in this manner, as in the case where the droplets are large, the scale adhesion preventing agent coating liquid is applied to the gap between the structure such as the cooling baffle and the inner wall of the polymerization container, or the back surface. It is extremely difficult to apply. Therefore, the conventional method using the two-fluid nozzle has a problem due to scale adhesion as in the method using the one-fluid nozzle.

[0005]

It is an object of the present invention to use a polymerization container having a large capacity, or a polymerization container having a plurality of cooling baffles and the like having a complicated internal structure. The scale adhesion inhibitor coating solution can be applied uniformly to the polymerization vessel, and a high-quality polymer can be obtained even after continuous operation over a long period without removing scale. It is to provide a method for producing a polymer.

[0006]

Means for Solving the Problems The present invention has a scale-preventing coating film on a portion which is in contact with a vinyl chloride monomer or a monomer mixture mainly composed of a vinyl chloride monomer during polymerization. In a method for producing a vinyl chloride polymer in which a suspension polymerization of the monomer is carried out in an aqueous medium in a polymerization vessel,

The above coating film has a particle size of 100 to 300 μm.
A method for producing a vinyl chloride-based polymer, which comprises spraying droplets of a scale-adhesion-preventing agent coating solution controlled to m into a polymerization container.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the method for producing a vinyl chloride polymer of the present invention, in forming a scale adhesion preventing coating film in a polymerization container to be used, the particle diameter is 100 to 300 μm, preferably 100 to 300 μm.
A droplet of the scale anti-sticking agent coating liquid controlled to 200 μm is sprayed into the polymerization container. If this particle size is too small, the scale anti-sticking agent coating liquid cannot be uniformly applied in the polymerization vessel. In addition, the amount of the scale anti-sticking agent coating liquid used is large and the coating time is long, which is not preferable. On the contrary, if the particle size is too large, the convection of the sprayed droplets in the polymerization container becomes insufficient, so, for example, when using a polymerization container with a complicated internal structure equipped with a plurality of cooling baffles, However, it becomes extremely difficult to apply a gap between the arranged baffle or the like and the inner wall of the polymerization container or the back surface of the baffle or the like.

As a method of spraying the droplets of the scale anti-adhesion agent coating solution into the polymerization container, for example, a gas phase portion of the polymerization container 1 as shown in FIG. 1, preferably the uppermost portion of the polymerization container is used. There is a method of spraying the scale adhesion preventing agent coating liquid at a predetermined pressure from the nozzle 2 arranged at.

The nozzle 2 may be either a one-fluid nozzle or a two-fluid nozzle, but the one-fluid nozzle is used because the purity of the carrier gas does not need to be inspected and a carrier gas supply device is unnecessary. Is preferred.

As a specific example of the one-fluid nozzle, for example,
Fan-shaped nozzles, straight-ahead nozzles, full-cone nozzles, empty-cone nozzles, fine spray nozzles, and the like can be mentioned. Specific examples of the two-fluid nozzle include circular nozzles, fan-shaped nozzles, and the like. Further, it is particularly preferable to use a full cone nozzle as shown in FIG. 3 and a fine spray with an internal core having an internal core 2B for strengthening the throttle in the vicinity of the orifice 2A of the full cone nozzle as shown in FIG. It is a nozzle. Further, the fine spray nozzle with an internal core is most preferable in that the same coating effect is exhibited even when the amount of the coating liquid used is small at the same injection pressure.

The scale anti-adhesion agent coating liquid may be jetted from such a nozzle so long as the scale anti-adhesive agent coating liquid is satisfactorily convected in the polymerization vessel. As shown in FIG. It is preferable to set the injection direction in both the top 1B direction and the bottom 1C direction of the polymerization container.

From such a nozzle, a particle size of 100-30
Examples of the method of spraying the droplets of the scale adhesion preventing agent coating liquid of 0 μm include a method of appropriately adjusting the orifice diameter of the nozzle used and the spray pressure of the scale adhesion preventing agent coating liquid. The selection range of the orifice diameter and the injection pressure is, for example, when the fine atomizing nozzle with the inner core is used as the nozzle, the injection pressure is 10 to 40 kg / cm ^2.
Is preferable, and more preferably 10 to 30 kg / cm ² . When the scale anti-adhesion agent coating liquid is jetted from the fine spray nozzle with the inner core under such conditions, droplets having a particle diameter of 100 to 300 μm can be easily obtained even when the jet pressure is the lower limit of the above range. The droplets easily flow into the air gap, for example, in the gap between the cooling baffle and the inner wall of the polymerization container, or on the back side. Therefore, even when a polymerization container having a plurality of such cooling baffles is used, The coating film can be uniformly formed in every corner of the container.

As the scale anti-adhesion agent coating liquid used in the present invention, the following scale anti-adhesion agent dissolved in an organic solvent such as water or alcohol such as methanol or ethanol can be used. The scale adhesion preventive agent concentration of the coating solution may be generally about 0.01 to 10% by weight.

The scale adhesion preventing agent is not particularly limited, and examples thereof include dyes, pigments, water-soluble polymer compounds, nitrites, nitrogen-containing aromatic compounds, hetero compounds, iodo compounds, pyrogallol derivatives, and phenolic compounds. ,
Aromatic amine compounds and the like can be used, and known scale anti-adhesive agents such as self-condensates of polyhydric phenols or self-condensates of polyhydric naphthols (JP-A-54)
No. 7487); a condensate of 1-naphthol and formaldehyde (JP-A-57-164107); a condensate of a phenol compound toaldehyde (JP-A-54-36389);
Mixed solution of quinone-amine compound and organic silica sol (JP-A-1-135802); naphthol sulfide compound (JP-A-4-311702); mixture of electron-donating dye and arylsulfonic acid and reaction thereof At least one selected from products (JP-A-5-70505); phenothiazine derivative (JP-A-5-501892); quinone compound, reduction product thereof or mixture thereof (JP-A-5-27).
9404); reaction product of ketone resin and phenolic compound (JP-A-62-236804); dye, pigment, aromatic compound having 5 or more conjugated π bonds or 5 or more conjugated π bonds A heterocyclic compound having (USP-4,757,124);
Polyaromatic amine (USP-4,024,330); Salt of cationic compound and anionic compound (GB-2,170,604); Reaction product of polyvinyl alcohol and aminobenzoic acid (EP-04981)
42A1); initial condensation modified products of phenols and aldehydes (JP-A-6-501884) and the like.
Particularly representative ones are self-condensates of polyhydric phenols such as pyrogallol, catechol and resorcinol, or 1,
Self-condensation products of polyhydric naphthols such as 3-dihydroxynaphthalene and 1,7-dihydroxynaphthalene (JP-A-54
-7487); 1,3-dihydroxynaphthalene,
Condensation products of naphthols such as 1,7-dihydroxynaphthalene and 1-naphthol with formaldehyde (JP-A-57 / 1982
-164107); a condensate of a phenolic compound such as phenol, pyrogallol, catechol, resorcinol and an aldehyde compound such as acetaldehyde, formaldehyde (JP-A-54-36389); o-phenylenediamine, m-phenylene Self-condensates of amino aromatic compounds such as diamine, p-phenylenediamine, diaminotoluene, diaminoxylene, diaminophenol, triaminobenzene, triaminotoluene, triaminoxylene (JP-A-51-50887); o- Aminophenol, m-aminophenol, p-aminophenol,
2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 2,3-diaminobenzoic acid,
2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,4-diaminobenzoic acid, 3,5-diaminobenzoic acid, 4,6-diaminoisophthalic acid, 2,5-diaminoterephthalic acid, 2, 6-diaminoterephthalic acid, 1,
Aromatic amine compounds such as 2-naphthylenediamine-7-sulfonic acid, 1,6-naphthylenediamine-4-carboxylic acid, α-naphthylamine, 1,5-diaminonaphthalene and 1,8-diaminonaphthalene, and p -Benzoquinone, chlor-p-benzoquinone, juroquinone, 6-methyl-1,4-naphthoquinone, α-naphthoquinone, lawson, condensate with an aromatic quinone compound such as β-naphthoquinone (JP-A-6-56911); p. -Aromatic amines such as phenylenediamine, p-aminophenol, 2-nitro-4-aminophenol, 2-aminodiphenylamine, 4,4'-diaminodiphenylamine, nitrobenzene, p-chloronitrobenzene, m-nitrobenzoic acid, Condensate with an aromatic nitro compound such as p-nitrobenzenesulfonic acid (Japanese Patent Laid-Open No. 5-23010) 8); a benzoic amino ester compound of partially saponified polyvinyl alcohol obtained by reacting partially saponified polyvinyl alcohol with aminobenzoic acid (EP-0498142A1); CI acid black 1, CI acid black 2, CI acid black 7, CI Acid Black 24, CI Basic Orange 2, CI Basic Orange 14, CI Basic Orange 15, CI Basic Orange 32, CI Basic Red 18, CI Basic Red 22, CI Solvent Red 3, CI Solvent Red 25, CI Solvent Black 3, CI Acid Brown 4, CI Acid Brown 13, CI Acid Green 7, CI Acid Green 35, CI Basic Violet 25, CI Disperse Blue 6, CI Disperse Blue 7, CI Disperse Blue 90, CI Basic Green 6, CI Sol Dyes such as cement yellow 33 (JP-A-61
-34006).

As the polymerization container used in the production method of the present invention, for example, as shown in FIGS. 1 and 2, a cylindrical straight body portion 1A and a substantially hemispherical top portion 1B and a bottom portion 1 which seal the upper and lower portions thereof are formed.
A substantially cylindrical polymerization container composed of C and the like can be mentioned. The inner volume of the polymerization container is preferably 80 m ³ or more, more preferably 100 m ³ or more. Further, a polymerization container suitable for use in the production method of the present invention has a cooling baffle 3 in the polymerization container 1 in addition to the nozzle 2 as shown in FIGS. 1 and 2. In particular, the cylindrical cooling baffle 3 is preferable because it has an excellent effect of preventing scale adhesion. The number of cooling baffles 3 arranged in the polymerization container 1 is
2-8 is preferable. Further, it is preferable to dispose a stirring blade 4 in the polymerization container 1. Examples of the stirring blade 4 include a paddle blade, a faradler blade, a bull margin blade, a propeller blade, a fan turbine blade, and the like, and among them, the paddle blade is preferable. The size of the stirring blade 4, the arrangement position, the number of blades, the number of blade rotations, and the like can be appropriately set depending on the size of the polymerization container and the type of the polymerization system. In the polymerization container used in the present invention, in addition to the nozzle 2, the cooling baffle 3, the stirring blade 4, etc.,
A jacket 5 for heating or cooling disposed around the straight body portion 1A (hereinafter referred to as jacket 5), and the top portion 1B.
It is preferable to have the reflux condenser 6 arranged in the above. As materials for the polymerization container 1, the cooling baffle 3, the stirring blades 4, etc., high chromium high purity ferritic stainless steel,
Stainless steel such as duplex stainless steel and austenitic stainless steel is preferred.

In the production method of the present invention, when polymerizing a vinyl chloride monomer or a monomer mixture mainly containing vinyl chloride monomer using such a polymerization vessel, the inside of the polymerization vessel is preferably washed with water. . The washing method is not particularly limited, and for example, as shown in FIGS. 1 and 2, a washing apparatus such as a fixed nozzle arranged in the gas phase portion of the polymerization container 1, a vertically movable fixed nozzle, a rotating nozzle, or the like. It can be performed by jetting water from 11. The washing with water may be performed when the polymerization is newly started, or after the polymerization is completed and the slurry is extracted.

Then, droplets having the above-mentioned particle diameter of the scale adhesion preventing agent coating liquid are sprayed from a nozzle arranged in the polymerization container. The spraying timing and the spraying amount can be adjusted by, for example, opening and closing a valve 9 arranged in the middle of a pipe 8 for supplying the scale adhesion preventing agent coating liquid to the nozzle 2 as shown in FIG. Even if the valve 9 is opened and closed manually, the controller 10 (for example, C
It may be automatically controlled by a PU or the like). In the production method of the present invention, by spraying such a scale adhesion inhibitor coating liquid, the inner wall surface of the polymerization vessel, a stirring blade, a stirring shaft,
Cooling baffles, headers, search coils, bolts, nuts, etc. where the monomers come into contact during polymerization, as well as the droplets of the scale adhesion inhibitor coating liquid convection flow to lower the polymerization container The gap between the baffle and the inner wall of the polymerization container,
Since the coating solution spreads to the back side of the stirring blade, etc., the scale anti-sticking agent coating solution can be uniformly applied to every corner of the polymerization container.

In the production method of the present invention, after the scale anti-adhesion agent coating liquid is applied in this manner, the scale application preventing film is formed by drying the coating liquid. The method for drying the scale anti-sticking agent coating liquid is not particularly limited,
For example, it may be left as it is for natural drying, or forced air may be forced into the polymerization container, or the inside of the polymerization container may be depressurized and dried. Moreover, the temperature of the applied part is 30 to 80.
You may heat-dry by the said jacket 5 so that it may become (degreeC).

In the production method of the present invention, the aqueous medium, the vinyl chloride monomer, and optionally other comonomers, dispersion aids, polymerization initiators and the like may be charged into the polymerization vessel in the same manner as in the prior art. The polymerization conditions may be the same.

Examples of the monomer to be polymerized by the production method of the present invention include vinyl chloride alone and a monomer mixture containing vinyl chloride as a main component (50% by weight or more of vinyl chloride). Examples of the comonomer copolymerized with vinyl chloride in this mixture include vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid esters or methacrylic acid esters such as methyl acrylate and ethyl acrylate; ethylene and propylene. Olefin; maleic anhydride; acrylonitrile; styrene; vinylidene chloride; and other monomers copolymerizable with vinyl chloride.

The above-mentioned dispersion aid may be one which is usually used for suspension polymerization of vinyl chloride monomer in an aqueous medium, and examples thereof include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose. Water-soluble cellulose ethers such as; saponified polyvinyl alcohol, acrylic acid polymers; water-soluble polymers such as gelatin; oil-soluble emulsifiers such as sorbitan monolaurate, sorbitan trioleate, glycerin tristearate, ethylene oxide propylene oxide block copolymers; Examples thereof include water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, and sodium laurate, which are added alone or in combination of two or more. It is possible.

The amount of the dispersion aid added is usually about 0.01 to 5 parts by weight per 100 parts by weight of the charged monomers.

The above-mentioned polymerization initiator may be one used in a known method for polymerizing vinyl chloride monomers, and examples thereof include diisopropyl peroxydicarbonate and di-
Percarbonate compounds such as 2-ethylhexyl peroxydicarbonate and diethoxyethyl peroxydicarbonate; t-butyl peroxyneodecanate, α
-Perester compounds such as cumyl peroxyneodecanate and t-butyl peroxyneodecanate; acetylcyclohexylsulfonyl peroxide, 2,4,4-
Peroxides such as trimethylpentyl-2-peroxyphenoxyacetate; azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis (4-methoxy-2,4-dimethylvaleronitrile); potassium persulfate; Examples thereof include ammonium persulfate and hydrogen peroxide, and these can be used alone or in combination of two or more.

The above-mentioned polymerization initiator may be added in an amount of usually about 0.01 to 3 parts by weight per 100 parts by weight of the charged monomers.

In the production method of the present invention, if necessary, a polymerization regulator, a chain transfer agent, a pH regulator, a gelation improving agent, an antistatic agent, etc., which are appropriately used for the polymerization of vinyl chloride monomer, are added. You can also do it.

[0027]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited thereto.

[Examples 1 and 2 and Comparative Examples 1 and 2] In this example, as the polymerization container, as shown in FIG. 1, a substantially cylindrical polymerization container 1 having an inner volume of 130 m ³ was used. 3 in the gas phase part of the same as the nozzle 2 (one-fluid nozzle) shown in FIG. 3 (referred to as nozzle type B in Table 1) or the fine spray nozzle with an inner core shown in FIG. 4 (one-fluid nozzle).
[Nozzle type A in Table 1] and a vertically movable nozzle as the water washing device 11, a heating or cooling jacket 5 around the container straight body part 1A, a reflux condenser 6 on the container top 1B, and an inner wall of the container. A polymerization vessel equipped with two cooling baffles 3 and a stirring blade 4 having a rotating shaft arranged at the center line of the vessel was used. The total number of nozzles 2 arranged in the polymerization container was 12. In addition, the nozzle 2
As shown in FIGS. 1 and 2, the arrangement of the four nozzles 2
The direction of spray of the scale anti-sticking agent coating liquid is set to the container top 1
It was set in the ring-shaped pipe 12 by setting it in the B direction, and the other eight nozzles 2 were arranged in the ring-shaped pipe 12 by setting the jetting direction of the scale adhesion inhibitor coating liquid to the container bottom 1C direction.

Washing step After washing the inside of the polymerization vessel with the washing apparatus 11 (water injection amount from the vertically movable nozzle: 20 m ² / hour, injection time: 5 minutes), the following scale anti-sticking agent application The liquid was applied.

Step of Applying Scale Adhesion Preventing Agent Coating Liquid C. I. 10 parts by weight of Direct Blue 1 and C.I. I.
2 parts by weight of Basic Blue 12 was mixed. Then, phytic acid was added to a 0.12% by weight aqueous solution of this mixture to adjust the pH of this aqueous solution to 3.0 to prepare a scale anti-sticking agent coating liquid. Next, the obtained scale anti-adhesion agent coating liquid was sprayed from the nozzle 2 under the conditions shown in Table 1 to apply the scale anti-adhesion agent coating liquid in the polymerization container. Table 1 shows the particle diameters (average particle diameters) of the droplets of the scale anti-sticking agent coating liquid obtained by this spraying.

Step of Forming Scale-Preventive Coating Film After applying the scale anti-sticking agent coating solution as described above,
Hot water of 50 ° C. was introduced into the jacket 5 to raise the temperature in the polymerization vessel. Then, the inside of the polymerization vessel was depressurized, and the coating liquid was dried for 10 minutes to form a scale adhesion preventing coating film. Then, the inside of this polymerization container was washed with the above-mentioned water washing device 11 (the amount of water jetted from the vertically movable nozzle: 2
0 m ² / hour, injection time: 3 minutes).

[0032]

[Table 1] In Table 1, nozzle type A is a fine spray nozzle with an internal core shown in FIG. 4, and nozzle type B is a full cone nozzle shown in FIG. Further, in Table 1, the injection pressure is the feed pressure in the feed pump of the scale adhesion preventing agent coating liquid.

Polymerization Step of Vinyl Chloride Monomer 57,500 kg of deionized water and 13.8 kg of partially saponified polyvinyl alcohol (suspension agent) are placed in a polymerization vessel having a scale-preventing coating film formed thereon as described above. Were mixed in advance and added. Next, the internal pressure of the polymerization container is 60 mmH
After evacuating to g, vinyl chloride monomer 46,000
0 kg was added. Then, the contents of the polymerization vessel are stirred with a stirring blade 4
While stirring at 2, 20.7 kg of di-2-ethylhexyl peroxydicarbonate (polymerization initiator) was press-fitted into the polymerization vessel with a pump, and at the same time a heating or cooling jacket 5
The contents of the polymerization vessel were heated to pass through and the polymerization was initiated.

During the polymerization, cooling water was conducted through the jacket 5 and the cooling baffle 3 and the reflux condenser 6 was operated to remove the heat of the polymerization reaction and maintain the polymerization temperature at 57 ° C. The polymerization was stopped when the internal pressure of the polymerization vessel reached 6.0 kg / cm ² (gauge pressure), and the residual unreacted monomer was recovered from the polymerization vessel. The polymerization time was 5 hours.
Then, the obtained polymer in a slurry state was extracted to the outside of the vessel, and the inside of the polymerization vessel was washed with the water washing device 11 (water injection amount from the vertically movable nozzle: 20 m ² / hour, injection). (Time: 5 minutes), the polymer remaining in the polymerization vessel was removed.

The above-mentioned washing step, the step of applying the scale anti-sticking agent coating solution, the step of forming a scale preventive coating film, and the step of polymerizing vinyl chloride monomer are defined as one batch, and the number of batches shown in Table 2 is used. After repeating, the state of scale adhesion inside the polymerization vessel was visually observed. The evaluation is shown in Table 2. Then, the polymer obtained in the final batch was dehydrated and dried, and the fisheye number measurement test described below was performed. Table 2 shows the results.

Fish Eye Number Measurement Test 100 parts by weight of the obtained polymer, 50 parts by weight of DOP, 0.1 part by weight of barium stearate, 0.1 part of cadmium stearate.
Parts by weight, cetanol 0.8 parts by weight, tin stabilizer 2.0 parts by weight, titanium dioxide 0.5 parts by weight and carbon black 0.1.
Parts by weight were kneaded with a 6 inch roll at 140 ° C. for 5 minutes.
Then, this kneaded product is processed into a sheet with a thickness of 0.3 mm,
The number of white transparent particles contained per 100 cm ^{2 of the} sheet was measured.

[0037]

[Table 2]

[0038]

According to the production method of the present invention, even when a large-capacity polymerization container is used or a polymerization container having a complicated structure in the polymerization container is used, the scale anti-adhesion agent coating liquid It can be applied uniformly inside. In addition, since continuous operation can be performed for a long period of time without removing the scale, it is possible to reduce the amount of scale anti-adhesion agent used and the coating time. And, even if it is continuously operated, a high-quality vinyl chloride polymer can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a polymerization container used in the manufacturing method of the present invention.

FIG. 2 is a plan view illustrating a polymerization container used in the manufacturing method of the present invention.

FIG. 3 is a cross-sectional view exemplifying a nozzle used for spraying a scale adhesion preventing agent coating liquid in the manufacturing method of the present invention.

FIG. 4 is a cross-sectional view exemplifying a nozzle used for spraying a scale adhesion preventing agent coating liquid in the manufacturing method of the present invention.

Claims (1)

[Claims] 1. A portion which is contacted with a vinyl chloride monomer or a monomer mixture mainly containing a vinyl chloride monomer during polymerization,
In a method for producing a vinyl chloride polymer in which a suspension polymerization of the monomer is carried out in an aqueous medium in a polymerization vessel having a scale adhesion preventing coating film, the coating film has a particle diameter of 100 to 300 μm. A method for producing a vinyl chloride polymer, which comprises spraying droplets of a controlled scale adhesion preventive agent coating liquid into a polymerization container.