JPH0881507A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE: To enable the continuous production of a high-quality polymer while hardly allowing scale deposition even when a large-sized polymerizer is used. CONSTITUTION: The production process comprises the step of washing a polymerizer with water, the step of applying. before the water film formed at the former step drys out, a scale inhibitor to the part of the polymerizer which is brought into contact with a monomer component (vinyl chloride or a mixture mainly comprising vinyl chloride) at the succeeding polymn. step and drying the inhibitor to form a coating film, and the step of conducting the suspension polymn. of the monomer component in an aq. medium in the polymerizer.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, when suspension polymerization is carried out in an aqueous medium of a vinyl chloride monomer, a polymer called "scale" adheres to the wall surface, baffles, stirring blades, etc. in the polymerization vessel. This scale reduces the heat transfer performance of the polymerization vessel,
Alternatively, when it is mixed in the obtained polymer, the polyvinyl chloride product obtained from the polymer is deteriorated in quality such as generation of fish eyes. For this reason, the polymerization vessel requires regular scale removal work.

On the other hand, development of a so-called scale adhesion preventive agent for preventing scale from adhering to the inside of a polymerization vessel or the like has been promoted, and at present, continuous operation without scale removal work up to several hundreds of batches. There is also a scale anti-sticking agent that makes it possible. The scale anti-adhesion agent is usually applied by spraying from a nozzle or the like installed in the gas phase portion above the polymerization container (Japanese Patent Publication No. 1-47).
481 gazette, Japanese Patent Publication No. 1-47482 gazette etc.).

By the way, in recent years, a polymerization container has been increased in size for the purpose of improving productivity. However, in a large and long polymerization vessel, the distance between the vapor phase part of the polymerization vessel where the nozzle is installed and the bottom of the polymerization vessel is large, so the scale adhesion inhibitor is applied evenly throughout the polymerization vessel. Difficult to do. In particular, it is difficult to apply a particularly uniform coating at the bottom of the polymerization container. As a result, when continuously operated, scale is gradually generated mainly from the bottom of the polymerization container, the fish eyes of the polyvinyl chloride product obtained by the scale increase, and the slurry extraction valve at the bottom is clogged, causing heavy weight. The problem arises that the extraction of the combined slurry is hindered.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to effectively prevent scale from adhering because the scale anti-adhesion agent can be uniformly applied in the polymerization vessel even if the polymerization vessel becomes large. The present invention provides a method for producing a vinyl chloride-based polymer, which enables continuous operation of a polymerization container for a long period of time and can continuously produce a high-quality polymer.

[0006]

The present invention is to wash the inside of a polymerization vessel with water; to prevent the scale from adhering to scale during the polymerization before the water film formed by the washing is exhausted. Coating and drying to form a coating film; vinyl chloride-based system having a step of suspension-polymerizing a vinyl chloride monomer or a mixture of vinyl-based monomers based on the vinyl chloride monomer in the polymerization vessel in an aqueous medium It is a method for producing a polymer.

Hereinafter, the present invention will be described in detail. As shown in FIG. 1, the manufacturing method of the present invention is a substantially cylindrical polymerization container having a cylindrical straight body part and a substantially hemispherical top and bottom parts that seal the upper and lower parts thereof, and has an internal volume of 100 m ³ or more. And the ratio of the length (L) of the straight body part to the inner diameter (D) of the polymerization container (L /
It is preferred that D) be applied to a polymerization vessel of 1.5 or higher.

According to the present invention, the inside of such a polymerization vessel is washed with water, and before the water film formed by the washing is exhausted,
A scale adhesion preventing agent is applied and dried to form a coating film. Here, “before the water film is completely dry” means at least before the water film at the portion where the monomer contacts during the polymerization is not completely dry, and preferably, it is formed by washing with water. The thickness of the water film in the body of the polymerization vessel is 0.01-3m
m, more preferably within the range of 0.01 to 1.5 mm. If the thickness of the water film is too thin, it may not be possible to uniformly apply the scale adhesion preventive agent described below, and the scale prevention effect may be shortened during continuous operation. Also, if it is too thick, the applied scale inhibitor may flow, and it is not economical because a large amount of scale adhesion inhibitor must be used.
Also, the effect of preventing scale adhesion is reduced.

There is no particular limitation on the washing of the polymerization vessel, and for example, a method using a washing apparatus such as a fixed nozzle installed in the gas phase above the polymerization vessel, a vertically movable fixed nozzle, or a rotating nozzle is preferable. . The polymerization vessel may be washed with water even when polymerization is newly started, after the polymerization is performed, the slurry is withdrawn and the polymerization vessel is washed with water. That is, the following modes can be mentioned as the case of continuous polymerization in which two or more polymerization batches are repeated.

(A) A polymer scale anti-adhesion agent is applied to a portion of the polymerization vessel which contacts the monomer during polymerization and dried to form a coating film. Suspension polymerization of a monomer or a mixture of vinyl-based monomers having the same as the main component is carried out in an aqueous medium, and (C) the polymer slurry obtained by the polymerization is extracted from the polymerization vessel, and then the inside of the polymerization vessel is washed with water. In the method for producing a vinyl chloride polymer in which a series of steps (A) to (C) are repeated, the following steps are carried out before the water film formed in the polymerization container by the washing in the step (C) is completely dry. (A) Apply the polymer scale adhesion preventive agent in the step.

The scale adhesion preventive agent used in the present invention 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 phenols. Compounds, aromatic amine compounds and the like can be used, and known scale adhesion inhibitors such as polycondensates of polyphenols and polynaphthols (JP-A-54-748).
7); 1-naphthol-formaldehyde condensate (JP-A-57-164107); phenol compound toaldehyde condensate (JP-A-54-36389); quinone-amine compound and organic Mixed solution with silica sol (JP-A-1-135802); naphthol sulfide compound (JP-A-4-311702); mixture and / or reaction product of electron-donating dye and aryl sulfonic acid
5-70505 publication);

Phenothiazine derivatives (JP-A-5-501892); quinone compounds and / or reduction products thereof (JP-A-5-279404); reaction products of ketone resins and phenolic compounds (JP-A-62) -236804); dyes, pigments, aromatic compounds having 5 or more conjugated π bonds, conjugated π
Heterocyclic compounds having 5 or more bonds (USP-4,757,12
4); 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
-0498142A1); initial condensation modified products of phenols and aldehydes (JP-A-6-501884) and the like.

Of these, preferred are self-condensates of polyhydric phenols such as pyrogallol, catechol and resorcinol, and polyhydric naphthols such as 1,3-dihydroxy-naphthalene and 1,7-dihydroxy-naphthalene. 54-7487); condensation products of naphthols such as 1,3-dihydroxy-naphthalene, 1,7-dihydroxy-naphthalene and 1-naphthol with formaldehyde (JP-A-57-164107); phenol, Condensation products of phenolic compounds such as pyrogallol, catechol, and resorcinol with aldehyde compounds such as acetaldehyde and formaldehyde (JP-A-54-36389);

Ortho, meta and paraphenylenediamine, diaminotoluene, diaminoxylene, diaminophenol, triaminobenzene, triaminotoluene,
Self-condensation products of aminoaromatic compounds such as triaminoxylene (JP-A-51-50887); ortho, meta or para aminophenol, 2,4- or 2,5-diaminobenzenesulfonic acid, 2,3-, 2,4-, 2,5
-, 3,4-, or 3,5-diaminobenzoic acid,
4,6-diaminoisophthalic acid, 2,5- or 2,
6-diaminoterephthalic acid, 1,2-naphthylenediamine-7-sulfonic acid, 1,6-naphthylenediamine-4
-Carboxylic acid, α-naphthylamine, 1,5-diaminonaphthalene, aromatic amine compounds such as 1,8-diaminonaphthalene and para-benzoquinone, chloro-para-benzoquinone, duroquinone, 6-methyl-1,4-naphthoquinone, Condensation products with aromatic quinone compounds such as α-naphthoquinone, Lawson, β-naphthoquinone (JP-A-6-56911)
Gazette);

Para-phenylenediamine, para-aminophenol, 2-nitro-4-aminophenol, 2-
Condensation products of aromatic amines such as aminodiphenylamine and 4,4′-diaminodiphenylamine with aromatic nitro compounds such as nitrobenzene, para-chloronitrobenzene, meta-nitrobenzoic acid and para-nitrobenzenesulfonic acid (JP-A-5230108). Gazette); 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, 2,
7 or 24, CI Basic Orange 2, 14, 15,
Or 32, CI Basic Red 18 or 22, CI Solvent Red 3, or 25, CI Solvent Black 3, CI
Dyes such as Acid Brown 4 or 13, CI Acid Green 7 or 35, CI Basic Violet 25, CI Disperse Blue 6, 7 or 90, CI Basic Green 6, CI Solvent Yellow 33 (JP-A-61-3
No. 4006).

The method for applying the scale anti-adhesive agent to the polymerization container is not particularly limited, and examples thereof include brush coating, spray coating, and a method of filling the polymerization container with the scale anti-adhesive agent and then withdrawing it. 57-6100
1, the same 55-36288, JP-B-56-501116,
The automatic coating methods described in JP-A-56-501117 and JP-A-59-11303 can also be used.

At least the inner wall surface, preferably the stirring blade, stirring shaft, baffle, condenser, header, search coil, bolt, nut, etc., is contacted with the monomer during polymerization as a place to apply the scale adhesion preventing agent. However, by applying the scale adhesion preventive agent when the water film has a thickness within the above range, the scale adhesion preventive agent is placed on the water film and the bottom of the polymerization container, the back side of the baffle, the stirring blade, etc. It becomes possible to spread evenly and evenly coat it in the polymerization can.

The method of drying the scale adhesion preventive agent applied in the polymerization container is not particularly limited, and for example, it may be allowed to stand as it is, or may be performed with ventilation or under reduced pressure.

The polymerization apparatus to which the production method of the present invention is applied is preferably equipped with the above-mentioned polymerization vessel, stirring blades, baffles, etc., as well as a heating or cooling jacket and a reflux condenser. As the stirring blade, for example, a paddle blade, a faradler blade, a bull margin blade, a propeller blade, a fan turbine blade and the like can be used, and among them, the paddle blade is preferable. The paddle blade size, installation position, number of blades, blade rotation speed and the like can be appropriately set depending on the size of the polymerization container and the polymerization system. The baffle may have a flat plate shape, a cylindrical shape, or the like, and may have 1 to 8 baffles. Such polymerization vessels, baffles,
As the material for the stirring blades, stainless steel such as high chromium high purity ferritic stainless steel, two-phase stainless steel, austenitic stainless steel, etc. is preferable.

In the production method of the present invention, suspension polymerization of a vinyl-based polymer will be described as an example. An aqueous medium, a vinyl chloride monomer, and optionally other comonomers, a dispersion aid, a polymerization initiator, and the like are introduced into a polymerization vessel. The agent and the like may be charged in the same manner as in the conventional case, and the polymerization conditions may be the same.

As the monomer to be polymerized, not only vinyl chloride but also a monomer mixture containing vinyl chloride as a main component (50% by weight or more of vinyl chloride) can be used, and a comonomer copolymerized with this vinyl chloride. Examples thereof include vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid esters or methacrylic acid esters such as methyl acrylate and ethyl acrylate; olefins such as ethylene and propylene; maleic anhydride; acrylonitrile;
Styrene; vinylidene chloride; and other monomers copolymerizable with vinyl chloride.

The above-mentioned dispersion aid may be one usually used in suspension polymerization of vinyl chloride in an aqueous medium,
For example, water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; partially saponified polyvinyl alcohol, acrylic acid polymers; water-soluble polymers such as gelatin, sorbitan monolaurate, sorbitan trioleate, glycerin tri Examples thereof include oil-soluble emulsifiers such as stearate and ethylene oxide propylene oxide block copolymers; water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, and sodium laurate. These are one or two kinds. The above combination can be added. The amount of the dispersion aid added is usually 0.01 to 5 parts by weight with respect to 100 parts by weight of the charged monomer.

The above-mentioned polymerization initiator may be one used in a known method for polymerizing vinyl chloride-based 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 trimethylbenzyl-2-peroxyphenoxyacetate; azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis (4-methoxy-2,4-dimethylvaleronitrile); and potassium persulfate , Ammonium persulfate, hydrogen peroxide and the like, and these can be used alone or in combination of two or more. The amount of the polymerization initiator added is usually 0.01 to 3 parts by weight with respect to 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 improver, an antistatic agent, etc., which are appropriately used for vinyl chloride-based polymerization, may be added. Is also optional.

[0025]

EXAMPLES The present invention will be described more specifically by showing examples and comparative examples. (Embodiment 1) The inner volume of a substantially cylindrical shape as shown in FIG.
A polymerization apparatus equipped with a 0 m ³ polymerization vessel, a heating and cooling jacket, a stirring blade, and a baffle was used. The ratio (L / D) of the length (L: 7,900 mm) of the straight body part to the inner diameter (D: 4,200 mm) of the polymerization container was 1.88. An aqueous device (20
The inside of the polymerization vessel was washed with m ³ / H × 2 set) for 5 minutes. When the thickness of the water film at the upper end of the straight body of the polymerization container becomes 0.1 mm and the thickness of the water film at the lower end of the straight body becomes 1 mm (after 15 seconds of water washing). Then, 100 liters of the following scale adhesion preventive agent was sprayed into the inside of the polymerization vessel from a spray nozzle installed on the top of the polymerization vessel.

Scale adhesion preventive agent C. I. 10 parts by weight of Direct Blue 1 and C.I. I.
After mixing 2 parts by weight of Basic Blue 12, a 0.12% by weight aqueous solution of this mixture was prepared, and phytic acid was added to this to prepare a 0.29% by weight aqueous solution to prepare a scale adhesion inhibitor. After the scale anti-adhesion agent was sprayed as described above, the jacket was heated to 50 ° C. and the pressure inside the polymerization vessel was reduced for 10 minutes to dry the scale anti-adhesion agent.
Then, it was washed again with the above-mentioned water washing device for 3 minutes.

Deionized water 57,500k was added to the polymerization vessel.
g and partially saponified polyvinyl alcohol 1 as a suspending agent
3.8 kg was added as an aqueous solution and added. After evacuating the inner pressure of the polymerization container to 60 mmHg, 46,000 kg of vinyl chloride monomer was charged, and while stirring, 20.7 kg of di-2-ethylhexyl peroxydicarbonate as a polymerization initiator was pumped into the polymerization container. The mixture was press-fitted into the inside, and at the same time, hot water was passed through the jacket to start the temperature rise and start the polymerization.

The polymerization reaction is carried out while maintaining the polymerization temperature at 57 ° C. When the internal pressure of the polymerization vessel reaches 6.0 kg / cm ² (gauge pressure), the polymerization is stopped, and the remaining unreacted unit amount is removed from the polymerization vessel. I recovered my body. The polymerization time was 5 hours.
The obtained polymer was taken out of the vessel in a slurry form, and then washed again with water to remove the polymer remaining in the polymerization vessel. The above-mentioned washing with water-application of polymer scale inhibitor, drying-polymerization operation was repeated 100 batches, and then the inside of the polymerization vessel was inspected to observe the scale adhesion state, and the polymer was dehydrated and dried to perform the following method. It was submitted to the test by. The results are shown in Table 1.

Measurement of bulk specific gravity: The polymer obtained was measured according to JIS K-6721. -Measurement of particle size distribution: JIS Z-88 for the obtained polymer
Sift using each of the # 60, # 100, and # 200 sieves according to 01,
The amount of passage was measured and expressed in% by weight. -Measurement of fish eye amount: 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 by weight of cadmium stearate, 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 at 140 ° C.
For 5 minutes mixing and kneading at inch roll, aliquoted as a sheet having a thickness of 0.3 mm, indicated by the number of white transparent particles in 100 cm ² of the sheet.

(Comparative Example 1) The thickness of the water film at the upper end of the straight body of the polymerization container was 0.000 mm, and the thickness of the water film at the lower end of the straight body was 0.005 mm. When (washing 5
Minutes later), the same procedure as in Example 1 was performed except that the following scale anti-sticking agent was applied.

[0031]

[Table 1]

[0032]

EFFECTS OF THE INVENTION According to the present invention, even if the size of the polymerization vessel is increased, scale is unlikely to adhere, and a high quality polymer can be continuously produced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a polymerization container used in the production method of the present invention.

Front page continuation (72) Inventor Yoshitaka Okuno 1 Towada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture Shin-Etsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A polymerization vessel is washed with water; a scale adhesion preventive agent is applied to a portion contacted with a monomer during polymerization before the water film formed by the water washing is exhausted, and the coating is dried to form a coating film. A method for producing a vinyl chloride-based polymer, which comprises the steps of forming and suspension-polymerizing a vinyl chloride monomer or a mixture of vinyl-based monomers mainly containing the vinyl chloride monomer in the polymerization container in an aqueous medium. 2. The manufacturing method according to claim 1, wherein
(A) to form a coating film by applying a polymer scale anti-adhesive agent to the portion where the monomer contacts during polymerization in the polymerization vessel, and drying,
(B) Suspension polymerization of a vinyl chloride monomer or a mixture of vinyl monomers mainly composed of this in the polymerization vessel in the polymerization vessel, and (C) polymerization of the polymer slurry obtained by the polymerization. In the method for producing a vinyl chloride-based polymer in which a series of steps (A) to (C) is repeated, which is performed by washing the inside of the polymerization container after withdrawing from the container, in the polymerization container by washing in the (C) step. A method for producing a vinyl chloride polymer, which comprises applying a polymer scale anti-adhesion agent in the following step (A) before the water film is completely dry.