JP3115953B2 - Polymerization vessel effective for preventing polymer scale adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymerization vessel useful for polymerizing monomers having an ethylenic double bond.

[0002]

2. Description of the Related Art Suspension polymerization of a monomer having an ethylenic double bond is usually carried out by using water, vinyl chloride, a polymerization initiator, a dispersant, and It is carried out by charging other various additives to be added and initiating the polymerization reaction. During the polymerization reaction, cooling water is removed by passing cooling water through a jacket and a reflux condenser to keep the reaction system at a predetermined temperature.

However, polymerization of vinyl chloride or the like has a problem of adhesion of a polymer scale in a polymerization vessel. Conventionally, as a method for preventing adhesion of the polymer scale, an inner wall of the polymerization vessel or other parts in contact with a monomer are used. A polymer scale adhesion inhibitor such as a dye, a pigment, a water-soluble polymer, a nitrite, a nitrogen-containing aromatic compound, a hetero compound, an iodine compound, a pyrogallol derivative, a phenolic compound, or an aromatic amine compound. Methods for forming a film are known.

[0004]

In recent years, from the viewpoint of occupational health and environmental measures, it has been attempted to reduce the frequency of inspecting and cleaning the inside of the polymerization reactor by opening the polymerization reactor. Therefore, there is a demand for a method for effectively preventing the growth of polymer scale adhering to the inside of a polymerization vessel when a long-term operation of about 20 batches or more is performed. However, only by the method of forming a coating film by applying the above-mentioned polymer scale anti-adhesive agent, the polymer scale grows, peels and mixes into the polymer when the above-mentioned long-term operation is performed. Further, there is a problem that the fisheye of the obtained product polymer is increased and the quality is lowered.

Accordingly, it is an object of the present invention to provide a method for effectively preventing the adhesion / growth of polymer scale in a polymerization vessel even when a long-term operation of about 20 batches or more is performed. An object of the present invention is to provide a polymerization vessel useful for the polymerization of a monomer having an ethylenic double bond, which can produce a high-quality polymer having few fish eyes with high productivity.

[0006]

In order to solve the above problems SUMMARY OF THE INVENTION The present invention is charged pipe leading to the gas phase portion in the polymerization vessel, the exhaust gas collection piping and reflux condenser lower connection pipe
The condensate generated on the inner surface of these pipes
An object of the present invention is to provide a polymerization vessel characterized in that the polymerization vessel projects from the inner wall of the polymerization vessel into the gas phase portion in the polymerization vessel so as not to be transmitted to the inner wall of the polymerization vessel. Hereinafter, the present invention will be described in detail with reference to the drawings.

In a conventional polymerization vessel, pipes leading to a gas phase in the polymerization vessel, for example, a charging pipe, a lower connection pipe of a reflux condenser, an exhaust gas recovery pipe, and the like, are substantially in contact with an inner wall of the polymerization vessel. To form the same plane. FIG. 3 is a simplified longitudinal cross-sectional view of a conventional polymerization vessel. In FIG. 3, the end face of the tip 2a of the pipe 2 is substantially in contact with the inner wall 1a of the polymerization vessel 1 even though there may be some irregularities. Are connected so as to form surfaces of the same height. Therefore, monomer, water vapor, and the like condensing upon contact with the inner surface of the pipe 2 will directly fall from the pipe tip 2a along the polymerization vessel inner wall 1a to the liquid phase section 4 in the polymerization vessel, and the liquid will always flow from the pipe tip 2a. The part 3 (the hatched part in FIG. 3) up to the upper surface 4a of the phase part 4 comes into contact with the condensed liquid. As a result, during the long-term operation, the wettability and adsorption of the coating film of the previously formed polymer scale anti-adhesive agent gradually deteriorate in the part 3 and the polymer scale anti-adhesion effect is impaired, The adhesion / growth of the polymer scale in the part 3 becomes remarkable.

[0008] In the polymerization reactor of the present invention, the leading end of the piping leading to the gas phase in the stacker of each of the charging pipe, the exhaust gas recovery pipe and the reflux condenser lower connection pipe has a polymerization reactor. It protrudes from the inner wall surface into the gas phase in the polymerization vessel. FIG. 1 is a longitudinal sectional view of a polymerization vessel showing a simplified polymerization vessel of the present invention,
In FIG. 1, a tip 2 a of a pipe 2 protrudes from an inner wall 1 a of the polymerization vessel 1 to a gas phase portion 5 in the polymerization vessel. Therefore, the condensate falls in the direction of arrow 6 without directly contacting the inner wall 1a of the polymerization vessel, and the effect of the coating film of the polymer scale adhesion preventive agent on the inner wall of the polymerization vessel is maintained even after long-term operation. And adhesion / growth of polymer scale can be prevented.

[0009] In the polymerization vessel of the present invention, the pipe leading to the gas phase in the polymerization vessel only needs to protrude to such an extent that the condensed liquid does not propagate to the inner wall of the polymerization vessel.
The protrusion may be 1 cm or more, preferably 1 to 10 cm.
Further, even if the tip of the pipe is substantially the same height as the inner wall surface of the polymerization vessel, it may not be protruded at a location where the condensed liquid does not reach the inner wall surface. The shape of the protruding tip of the pipe is not particularly limited, and for example, the tip may have an acute angle to improve drainage. In addition, as a method of projecting the above-mentioned pipe into the gas phase portion in the polymerization vessel, a method of inserting the pipe into the polymerization vessel may be mentioned, but a conventional polymerization vessel is used in that a conventional polymerization vessel can be used. A method of attaching a lip to a tip portion of the pipe provided in the above. FIG.
FIG. 3 is a simplified view of a lip portion of a polymerization vessel having a lip attached to a tip of a pipe leading to a gas phase portion. As shown in FIG. 2, the tip of the lip 7 may be sharpened to improve drainage. For the material of the lip to be attached to the tip, from the viewpoint of corrosion resistance, 18-8 austenitic, 13 chromium ferrite, martensite, 18 chromium ferrite, high chromium ferrite, It is preferable to use a phase-based austenitic / ferritic stainless steel or the like.

The polymerization vessel of the present invention may be of a conventionally known type. In addition to the above-described charging pipe, exhaust gas collecting pipe, and reflux condenser, for example, a stirrer,
Use a baffle, jacket, etc. As the stirrer, a stirrer having a stirrer in the form of a paddle, a faudler, a bull margin, a propeller, a turbine, or the like is used in combination with a baffle such as a flat plate, a cylinder, or a hairpin coil as necessary.

When a monomer having an ethylenic double bond is polymerized using the polymerization vessel of the present invention, various known techniques for preventing polymer scale adhesion can be used in combination. Preferably, a conventionally known polymer scale adhesion inhibitor is applied in advance to form a coating film. By forming the coating film of the polymer scale adhesion inhibitor, the adhesion of the polymer scale is prevented.

Examples of the polymer scale adhesion inhibitor include dyes, pigments, water-soluble polymers, nitrites, nitrogen-containing aromatic compounds, heterocyclic compounds, iodine compounds, pyrogallol derivatives, phenolic compounds, and aromatic amines. Compounds and the like, specifically, JP-B-46-16084,
No. 30343, No. 46-4753, No. 45-37988, No. 46-2082
No. 1, No. 45-30835, No. 48-29795, No. 51-21672
Nos. 51-37306, 51-37308, 51-24953
Nos. 53-6023, 53-6024, 53-6025, 53
No.-6026, No.53-21908, No.53-28347, No.53-28
No. 348, No. 53-46235, No. 59-1413, No. 58-13564
Nos. 56-5442, 56-5443, 56-5444, 59
−34721, 58−11884, 60−6361, 59−31
No. 522, No. 60-48522, No. 60-48523, No. 51-1471
No. 51-1472, No. 57-59243, No. 55-5523, No.
56-22445, 56-22447, 57-31730, 57
−47922, 60−59246, 61−25730, 52−
24070, 55-4327, 58-12893, 58-1444
No. 4, No. 58-14445, No. 58-14446, No. 58-14447
Nos. 60-42245, 61-21247, 61-842,
No. 61-843, No. 49-2992, No. 53-36509, No. 57-
Nos. 34286, 60-40444 and 60-59247;
-195702, 57-198710, 58-11504, 58-
180509, 58-180510, 59-78210, 60-20
No. 909, No. 54-50089, No. 54-101889, No. 55-2143
No. 6, No. 55-73709, No. 55-98207, No. 55-112209
No. 58-8709, No. 58-61104, No. 58-168607,
No. 58-180511, No. 58-204006, No. 60-71614, No.
55-54305, 55-54317, 57-192413, 57
-192414, 59-129207, 61-7309, 53-10
Nos. 8187, 59-184202, 59-202201, 59-2109
No. 02, No. 60-47002, No. 60-71601, No. 60-72902
No. 60-96603, No. 60-233103, No. 61-31406
Nos. 61-34006, 61-51001, 61-51002
Nos. 55-155001, 55-155002, 56-112903
Nos. 58-69203, 58-101103, 58-103503
And Nos. 58-210902, 59-11303, and 59-170102.

The monomer having an ethylenic double bond which is polymerized by using the polymerization vessel of the present invention includes, for example, vinyl halides such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; Acid, methacrylic acid, and their esters or salts; maleic acid, fumaric acid, and their esters or anhydrides; diene monomers such as butadiene, chloroprene, and isoprene; styrene, acrylonitrile, vinylidene halide, and vinyl ether. No. These are used alone or in combination of two or more.

When a vinyl chloride polymer is produced by using the polymerization vessel of the present invention, a method for charging an aqueous medium, a monomer such as vinyl chloride, a polymerization initiator, a dispersant, etc., into the polymerization vessel,
The charge ratio, other polymerization reaction conditions, and the like may be performed in the same manner as in the conventionally known method. Also, upon polymerization,
A polymerization regulator, a chain transfer agent, a pH regulator, a gelling improver, an antistatic agent, a cross-linking agent, a stabilizer, a filler, and an antioxidant that are appropriately used in the production of a vinyl chloride polymer, if necessary. It is also optional to add a buffer and the like.

[0015]

Example 1 A stainless steel jacket having an inner volume of 2.1 m ³ , a reflux condenser, a charging pipe, an exhaust gas collecting pipe, a stirrer, and a polymerization vessel equipped with a baffle were used. Various pipes for charging and the like provided in the polymerization vessel were of a conventional type in which the end surface of the tip was worked so as to be substantially the same as the inner wall surface of the polymerization vessel. A lip shown in FIG. 2 was attached to the top of the reflux condenser, charging pipe, and exhaust gas collecting pipe of the polymerization vessel. 10 g of CI Direct Blue 1 and 2 g of CI Basic Blue 12 were dissolved in 10 liters of ion-exchanged water as a polymer scale adhesion inhibitor, and an aqueous solution containing 17 g of phytic acid was added to the inner wall of the polymerization vessel, stirring blades, baffles and piping. It was applied to the entire surface, dried at 50 ° C. for 10 minutes, and washed with water.

Thereafter, 840 kg of deionized water is added to the polymerization vessel.
And 240 g of partially saponified polyvinyl alcohol and 160 g of cellulose ether were added as an aqueous solution. 50 mm inside the container
After degassing to Hg, 670 kg of vinyl chloride monomer was charged, and 470 g of di-2-ethylhexylperoxydicarbonate was further injected with a pump while stirring. The temperature was raised to 57 ° C. by passing hot water through the jacket of the polymerization vessel. After the start of the reaction, the polymerization was continued while removing heat by passing cooling water through the jacket and cooling water through the condenser. The internal pressure of the polymerization vessel
Unreacted monomers were recovered at the time when the pressure dropped to 6.5 kg / cm ² G, and the polymer was taken out of the vessel in the form of slurry, and the inside of the polymerization vessel was washed with water. The operation from the application of the polymer scale adhesion inhibitor to the water washing in the polymerization vessel through the polymerization is continuously continued for 50 batches, and then the adhesion of the polymer scale in the polymerization vessel /
The growth situation was examined. Table 1 shows the results.

The bulk specific gravity, particle size distribution and fish eye of the polymer obtained after 50 batches were measured by the following methods. Table 1 shows the results. (1) Bulk specific gravity: Measured according to JIS K 6721. (2) Particle size distribution: # 48, # 60, # 80, according to JIS Z 8801
The mixture was sieved using each of # 100, # 150, and # 200 sieves, and the passing amount (% by weight) was measured. (3) Fisheye: 100 parts by weight of the sample vinyl chloride polymer, 1 part by weight of tribasic lead sulfate, and lead stearate
A mixture prepared by mixing 1.5 parts by weight, 0.2 parts by weight of titanium oxide, 0.1 parts by weight of carbon flux and 50 parts by weight of dioctyl phthalate was kneaded for 5 minutes at 145 ° C. using a roll, and then a sheet having a thickness of 0.2 mm was prepared. Molded into sheet 100
The number of fish eyes per cm ² was counted.

Comparative Example 1 A polymer was produced in the same manner as in Example 1 except that a charging pipe, a reflux condenser, and an exhaust gas collecting pipe were used without attaching a lip to the tip.
In the same manner as in Example 1, the scale adhesion state in the polymerization vessel and the bulk specific gravity, particle size distribution and fish eye of the obtained polymer were examined. Table 1 shows the results.

[0019]

[Table 1]

[0020]

According to the present invention, when a monomer having an ethylenic double bond is polymerized using the polymerization vessel of the present invention, even if a long-term operation of about 20 batches or more is performed, adhesion of the polymer scale in the polymerization vessel can be obtained. / The growth can be effectively prevented. Therefore, a high quality polymer having few fish eyes can be produced with high productivity.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a polymerization vessel in which a polymerization vessel of the present invention is simplified.

FIG. 2 is a simplified view of a lip portion of the polymerization vessel of the present invention, in which a lip is attached to a tip of a pipe leading to a gas phase portion.

FIG. 3 is a longitudinal sectional view of a conventional polymerization vessel, which is simplified.

[Explanation of symbols]

 1a Polymerizer inner wall 2 Piping leading to gas phase in polymerization reactor 2a Tip of piping leading to gas phase in polymerization reactor

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Maruyama 1 Kazu-gun, Kashima-gun, Ibaraki Pref., Kashima Plant Shin-Etsu Chemical Co., Ltd. Address Shin-Etsu Chemical Co., Ltd. PVC Research Institute (56) References JP-A-61-81408 (JP, A) JP-A-1-203406 (JP, A) JP-A-54-73889 (JP, A) Sho-62-109739 (JP, U) JP-B-49-2335 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/00-2/60 C08G 85/00

Claims (1)

(57) [Claims] 1. A lead to the gas phase portion of the polymerization vessel was charged pipe, exhaust gas collection piping and reflux condenser lower connection pipe
The condensate generated on the inner surface of these pipes
A polymerization vessel protruding from the inner wall of the polymerization vessel into a gas phase portion in the polymerization vessel so as not to be transmitted to the inner wall of the polymerization vessel.